Emotionally, your child is now better developed. She now knows and understands what causes certain feelings and even knows that others can react differently to the same situation. This understanding is now helping your child to have better social interaction with her peer groups. She is willing to listen and be patient for her turn. She is more sympathetic and can empathize with other kids of her group.
What you need to know
To make it possible for her to have better socio-emotional development, give her as many opportunities as possible to interact with other kids. This will help her to better understand others emotions and also have more control over her own emotions. You will notice that now when she is with her peers and wants to have her turn with the toy, instead of throwing a fit she will be calmly negotiating and waiting for her turn.