Can my family member access to my data and information stored if they can be share to use the iCloud space

See the following Apple articles:

Set up Family Sharing

Set up Family Sharing - Apple Support

See this article: What is Family Sharing?

What is Family Sharing? - Apple Support

-> When you share iCloud+, family members can't see each others’ photos, files, or documents. 

Make sure that each family member has a unique Apple ID

Make sure that each family member has a unique Apple ID - Apple Support

Download family members’ purchases on iPhone

Download family members’ purchases on iPhone – Apple Support (UK)

Add a family member to your subscriptions from Apple

Add a family member to your subscriptions from Apple – Apple Support (UK)