1. The contraction he's can mean he is OR he has. Similarly, she's can mean she is OR she has, and it's can mean it is OR it has, and John's can mean John is OR John has.
Example :
1. He is working
2. He has finished.
3. She is here.
4. She has left.

2. The contraction he'd can mean he had OR he would. Similarly, they'd can mean they had OR they would.
Example :
1.He had eaten when I arrived.
2. He would eat more if possible.
3. They had already finished.
4. They would come if they could.