Verbs follow regular and predictable patterns. When you know some verbs very well, you know how the verbs change in the past, for the future, for one person who is speaking, for the person listening, etc. You have regular patterns - the changes in the verb are regular, and predictable. There are always exceptions and complex changes in other verbs, especially some common verbs, but most verbs are regular. If you know the pattern, you know how to use other verbs, that you have just learned.

I guess it's mean the shapes of a verb according tences or the context of sentence