It's called your ResearchGate score. According to ResearchGate:
"The RG Score takes all your research and turns it into a source of reputation. It is calculated based on the research in your profile and how other researchers interact with your content."
This score often rises when you are active in answering questions or asking questions, publish research on ResearchGate, and when ResearchGate encounters your citations.
This number is RG scores. The RG score is depends on the number of publications, reads, citations and followers, also participating in the Q&A. This RG Score represents user's activities within the Research Gate site.