While every child develops at a different rate, typically by the age of five your child really is into friends. They like to please friends, they like to be with their friends. They know girls verses boys and sometimes they like to be with their own kind. So if you have a little girl and they want to play with the girls, that's very natural.
They also like to sing, dance, and act. So they're very into more dramatic play and encouraging opportunities such as putting them in a dance class or putting them into some kind of music class is a great time because they're very into it. They also really like to agree with the rules or they at least have an appreciation for the rules and they will tell you if someone is breaking the rules which is kind of fun to see, you know if they're telling you that Johnny's not listening at the playground, well he might not be.
So this is a time where you can really encourage your child to do the things that they like to do and encourage more play dates, get them involved with their friends, putting them in organized classes or sports is really great at this age.