He is demonstrating using Get Integer, Integer - Integer and Set Integer nodes to minus 1 from Life every time an event is triggered.
You can copy this text and then right-click in the event graph of a Blueprint to recreate it:
Begin Object Class=K2Node_VariableGet Name="K2Node_VariableGet_103"
Begin Object Class=EdGraphPin Name="EdGraphPin_4098"
End Object
Begin Object Class=EdGraphPin Name="EdGraphPin_4097"
End Object
Begin Object Name="EdGraphPin_4098"
PinName="self"
PinType=(PinCategory="object",PinSubCategory="self")
bHidden=True
End Object
Begin Object Name="EdGraphPin_4097"
PinName="Life"
Direction=EGPD_Output
PinType=(PinCategory="int")
DefaultValue="0"
AutogeneratedDefaultValue="0"
LinkedTo(0)=EdGraphPin'"K2Node_CallFunction_10004.EdGraphPin_4100"'
End Object
VariableReference=(MemberName="Life",bSelfContext=True)
Pins(0)=EdGraphPin'EdGraphPin_4097'
Pins(1)=EdGraphPin'EdGraphPin_4098'
NodePosX=368
NodePosY=16
NodeGuid=AC6C208746BFBD473D44D8A361429A2F
End Object
Begin Object Class=K2Node_CallFunction Name="K2Node_CallFunction_10004"
Begin Object Class=EdGraphPin Name="EdGraphPin_4099"
End Object
Begin Object Class=EdGraphPin Name="EdGraphPin_4100"
End Object
Begin Object Class=EdGraphPin Name="EdGraphPin_4101"
End Object
Begin Object Class=EdGraphPin Name="EdGraphPin_4102"
End Object
Begin Object Name="EdGraphPin_4099"
PinName="self"
PinFriendlyName="Target"
PinToolTip="object'KismetMathLibrary' Target\n"
PinType=(PinCategory="object",PinSubCategoryObject=Class'/Script/Engine.KismetMathLibrary')
DefaultObject=Default__KismetMathLibrary
bHidden=True
End Object
Begin Object Name="EdGraphPin_4100"
PinName="A"
PinToolTip="int A\n"
PinType=(PinCategory="int")
DefaultValue="0"
AutogeneratedDefaultValue="0"
LinkedTo(0)=EdGraphPin'"K2Node_VariableGet_103.EdGraphPin_4097"'
End Object
Begin Object Name="EdGraphPin_4101"
PinName="B"
PinToolTip="int B\n"
PinType=(PinCategory="int")
DefaultValue="1"
AutogeneratedDefaultValue="0"
End Object
Begin Object Name="EdGraphPin_4102"
PinName="ReturnValue"
PinToolTip="int Return Value\n"
Direction=EGPD_Output
PinType=(PinCategory="int")
DefaultValue="0"
AutogeneratedDefaultValue="0"
LinkedTo(0)=EdGraphPin'"K2Node_VariableSet_75.EdGraphPin_4105"'
End Object
bIsPureFunc=True
FunctionReference=(MemberParentClass=Class'/Script/Engine.KismetMathLibrary',MemberName="Subtract_IntInt")
Pins(0)=EdGraphPin'EdGraphPin_4099'
Pins(1)=EdGraphPin'EdGraphPin_4100'
Pins(2)=EdGraphPin'EdGraphPin_4101'
Pins(3)=EdGraphPin'EdGraphPin_4102'
NodePosX=560
NodeGuid=127AB91C4130AF22F9EA9D8F2FF294D2
End Object
Begin Object Class=K2Node_VariableSet Name="K2Node_VariableSet_75"
Begin Object Class=EdGraphPin Name="EdGraphPin_4103"
End Object
Begin Object Class=EdGraphPin Name="EdGraphPin_4104"
End Object
Begin Object Class=EdGraphPin Name="EdGraphPin_4105"
End Object
Begin Object Class=EdGraphPin Name="EdGraphPin_4106"
End Object
Begin Object Name="EdGraphPin_4103"
PinName="execute"
PinType=(PinCategory="exec")
LinkedTo(0)=EdGraphPin'"K2Node_Event_96.EdGraphPin_4108"'
End Object
Begin Object Name="EdGraphPin_4104"
PinName="then"
Direction=EGPD_Output
PinType=(PinCategory="exec")
End Object
Begin Object Name="EdGraphPin_4105"
PinName="Life"
PinType=(PinCategory="int")
DefaultValue="0"
AutogeneratedDefaultValue="0"
LinkedTo(0)=EdGraphPin'"K2Node_CallFunction_10004.EdGraphPin_4102"'
End Object
Begin Object Name="EdGraphPin_4106"
PinName="self"
PinType=(PinCategory="object",PinSubCategory="self")
bHidden=True
End Object
VariableReference=(MemberName="Life",bSelfContext=True)
Pins(0)=EdGraphPin'EdGraphPin_4103'
Pins(1)=EdGraphPin'EdGraphPin_4104'
Pins(2)=EdGraphPin'EdGraphPin_4105'
Pins(3)=EdGraphPin'EdGraphPin_4106'
NodePosX=720
NodePosY=-112
NodeGuid=7A146CC447E95FD25AFB289C83752415
End Object
Begin Object Class=K2Node_Event Name="K2Node_Event_96"
Begin Object Class=EdGraphPin Name="EdGraphPin_4107"
End Object
Begin Object Class=EdGraphPin Name="EdGraphPin_4108"
End Object
Begin Object Class=EdGraphPin Name="EdGraphPin_4109"
End Object
Begin Object Class=EdGraphPin Name="EdGraphPin_4110"
End Object
Begin Object Name="EdGraphPin_4107"
PinName="OutputDelegate"
Direction=EGPD_Output
PinType=(PinCategory="delegate",PinSubCategoryObject=Function'/Script/Engine.BTDecorator_BlueprintBase:ReceiveTick')
End Object
Begin Object Name="EdGraphPin_4108"
PinName="then"
Direction=EGPD_Output
PinType=(PinCategory="exec")
LinkedTo(0)=EdGraphPin'"K2Node_VariableSet_75.EdGraphPin_4103"'
End Object
Begin Object Name="EdGraphPin_4109"
PinName="OwnerActor"
Direction=EGPD_Output
PinType=(PinCategory="object",PinSubCategoryObject=Class'/Script/Engine.Actor')
End Object
Begin Object Name="EdGraphPin_4110"
PinName="DeltaSeconds"
Direction=EGPD_Output
PinType=(PinCategory="float")
End Object
EventSignatureName="ReceiveTick"
EventSignatureClass=Class'/Script/Engine.BTDecorator_BlueprintBase'
bOverrideFunction=True
Pins(0)=EdGraphPin'EdGraphPin_4107'
Pins(1)=EdGraphPin'EdGraphPin_4108'
Pins(2)=EdGraphPin'EdGraphPin_4109'
Pins(3)=EdGraphPin'EdGraphPin_4110'
NodePosX=496
NodePosY=-144
NodeGuid=BCA082DD4AFECACB8E72FBA87E35DE6E
End Object