A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Whether is legit, depends on definition.
Microsoft works with partners. Partners promote their services, products etc.
You might have attended a Microsoft event and at registration, allowed Microsoft or its partners to contact you.
Sometimes Microsoft also does joint events, or organizes thematic events with partners as speakers.
This is very common in the Microsoft eco-system.
In that it is a commercial marketing event, or a briefing, whether paid or free.
It would unlikely be a scam.
Checking out the details and verifying the organizers would be the way to go.
If there are further doubts you can consider posting the invite here.