You can check the current movement mode of the chracter, when the character is on ground the default movement mode is walking if you are in the air the default is falling.
To do this you can drag the character movement from the components tab to the blueprint or right click in the blueprint e type get character movement. Then from character movement drag a wire and get movement mode, drag from movement mode and type switch on movement mode. On the switch node you can click the arrow down to show all movement modes you can use to execute your animations.
If you still want to get the character velocity just get the character movement component and from there drag an get velocity node.
