A child may have basic bilingualism - when they can speak with family members and other adults but are behind monolingual children of the same age. Or they may have native-like ability - where their level of spoken language is hard to tell apart from their monolingual peers.
Whatever degree of proficiency you achieve, bilingualism or multilingualism can be a positive and enriching part of life. Especially for children and families who speak two or more languages either in the home or in the community.