Grammatical conjugation is like code words that helps us know who is doing the action (the verb) and when it is happening. It's kind of like saying "I jump" versus "she jumps." The word "jump" stays the same, but we add special endings to the word depending on who is doing the jumping and when it is happening.
So, let's say we have the word "play." If we want to say "I play," we add a special ending to the word and say "I play." If we want to say "you play" we add a different ending and say "you play." And if we want to say "they play" we add yet another ending and say "they play."
Conjugation might seem a little confusing, but it helps us communicate better by giving us extra information about who is doing the action and when it is happening.