You have a corrupted or incomplete installation. First run a Steam Verify operation against the game.
If that doesn't help, do a full clean re-install:
- move any valued save games elsewhere
- "uninstall" in Steam-Vic3
- manually delete both the Steam/SteamApps/common/Victoria3 AND Documents/Paradox Interactive/Victoria3 folders
- re-install game in Steam, run a Steam Verify when done.
- add Victoria3.exe to the exceptions list of your antivirus app; ESPECIALLY if you have Windows Defender, add it to the Ransomware "Apps Allowed Through" list.
- start the game with no mods active and test
In particular make sure there are no files or folders left under either the Steam Victoria3 or Documents Victoria3 locations, before installing again.
All the best!