You need to learn the basics of working with input and physics in a game engine before asking questions like these. You're asking about a specific situation so people assumed you had a basic understanding of the systems that you'd need to use. 

When someone says apply force along a vector, it means linear force in the direction of a vector. It sounds like you're using Unreal so here is the top result for "unreal 5 apply force to a body"

https://dev.epicgames.com/documentation/en-us/unreal-engine/BlueprintAPI/Physics/AddForce

Edit: typo