Transitivity in grammar is like playing with Legos! Just like how you can connect different Lego pieces to make a bigger structure, in a sentence, you can also connect different parts to make a bigger meaning.
Some words in a sentence are called verbs, which are like the building blocks in Lego. Verbs describe an action or a state of being. But some verbs need another part, like an object or a complement, to complete their meaning.
For example, if you say "I read", it doesn't really make sense without any other information. But if you say "I read a book", now it's a complete idea. "Read" is a transitive verb because it needs an object (book) to complete its meaning.
So transitivity is like making sure all the right Lego pieces are connected to make a meaningful sentence. It helps us communicate clearly and understand each other.