This stands for "Web Download." It indicates that the file was sourced directly from a streaming service (like Hulu or Amazon Prime) without being re-encoded. This usually results in a cleaner image compared to "WebRips."
When you see a filename like it refers to the technical quality of the video: Deep Water -2022- WEB-DL 1080p -Vegamovies.NL-.mkv
This is Full High Definition. On most modern TVs and monitors, 1080p provides a crisp, clear picture that captures the moody, atmospheric cinematography of the film. This stands for "Web Download