At six, your child will probably be communicating well, though kids of this age can still get tangled up in tenses. Between seven and eight, most language difficulties are resolved.

It's normal for school-age children to trip over grammar occasionally and to get words confused.
By about six or seven years, your child will probably:
By seven or eight, your child will be able to explain thoughts and ideas, join in conversations, and tell detailed stories about daily events.
Communicating with your child
Your school-age child might not always talk about any troubles at school or with friends. School children might need your help to open up and share any concerns.
One way to do this is to ask your child open-ended questions, such as, ‘What did you enjoy about school today?’ These questions encourage more than a ‘yes’ or ‘no’ answer, and can help your child to raise tricky topics.
Research shows that your child’s language will benefit greatly if you take the time to listen and chat together.
To encourage talking and vocabulary expansion, you can:
Rubin, K.H., Bukowski, W., & Parker, J.G. (1998). Peer interactions, relationships and groups. In W. Damon (Series Ed.) & N. Eisenberg (Vol Ed.), Handbook of child psychology: Vol. 3. Social, emotional and personality development (5th ed.). New York: Wiley.
Saarni, C., Mumme, D.L., & Campos, J.J. (1998). Emotional development: Action, communication, and understanding. In W. Damon (Series Ed.) & N. Eisenberg (Vol Ed.), Handbook of child psychology: Vol. 3. Social, emotional and personality development (5th ed.). New York: Wiley.