Primary 2 needs a tuition?

I would recommend to get them attend language classes. It's very important to be bilingual and there is no better time to start now because they have to start young ~ Kids also learn new language faster! Personally, I was raised speaking two languages but I found that it's more challenging to get the kids to do that in current environment. You can consider sending them to Le Xue Education if you're looking to improve your child's Mandarin. Their tutors are experienced and passionate.

Depends how your child is coping in school. My kids go for enrichment classes and their lessons are faster than in school so they are doing very well in school. Entirely up to you. If your child is struggling, you may want to check with the teacher how you can help or if the teacher can help. If your child is coping well in school, maybe you can hold on if time is a concern. Hope this helps.

If she need that extra help for that particular subject,is fine

Check with your child's form teacher to see if your lo needs tuition.

Can see if school have such extra lesson??

If you feel it's weak, it's fine.