Whoa! I actually recognized this. It's an art installation at Amsterdam Schiphol Airport's D-Gates! My son was climbing into one of the letters, so I guess that memory is somehow burned into my brain. Fascinating.

It's supposed to say "So Go On"

https://www.schiphol.nl/en/blog/an-artistic-start-to-your-journey/#%3A%7E%3Atext=Message+to+travellers-%2CIf+you+have+ever%2C-been+on+Schiphol%E2%80%99s