The verb 'serais' is the way to say 'would be' when talking about something that might happen in the future or in a different situation.
When you use 'serais', you are talking about something that could happen, but you are not sure.
Examples:
If I had more time, I serais able to finish my drawing.
She serais happy if she got a new toy.
He serais a good doctor if he studied hard.
I serais a superhero if I had superpowers.
If I had a magic wand, I serais able to fly.
She serais a princess if she lived in a castle.