What does "100W. 33rd" mean here?

You are ignoring the space between 100 and W. Yes, in street addresses, the native speaker would recognize that that means number 100 (building or house number 100) West Thirty-third Street. It's not a famous way of numbering buildings, it's just the common way of doing so. When writing such an address, always leave a space between the building or house number and the directional abbreviation. Number 15 South Front Street would be written: "15 S. Front St." Number 85 East Memorial Drive would be written "85 E. Memorial Dr."