When writing with active voice, the subject performs the action.
Bob drives the truck.
Mom baked a cake.
Sarah opened her gifts.
In passive voice, the subject does nothing. Instead, the action happens to the subject.
The truck is driven by Bob.
The cake was baked by Mom.
The gifts were opened by Sarah.
Did you notice something? Each of the passive voice sentences uses the word by. In each of those sentences, the action is being done by somebody else. The subject of the sentence is just passively having action done to it.
Active voice is a stronger voice in writing. Try to use active voice. Make your subject do the action.
▶Now you try it. Change this passive voice sentence into a sentence with active voice. The ball was thrown by Tom. Did you make Tom the subject and let him do the action? Good for you!