What a browser fingerprint is
A browser fingerprint is the set of device and browser parameters that can identify you even without cookies: user-agent, screen resolution, language, time zone, CPU cores and more. The more unique the set, the easier you are to track.
How to reduce tracking
A VPN hides your IP and location but not the fingerprint itself. GANVAS VPN protects your traffic and swaps your IP; against fingerprinting, use privacy-focused browsers. Also check your WebRTC leak and IP address.