Based on the search results, R63 can refer to different things depending on the context. Here are the possible meanings:

• R63 (South Africa): A road in South Africa.
• HMS Concord (R63): A destroyer of the Royal Navy.
• HMS Venerable (R63): An aircraft carrier of the Royal Navy.
• R63 (Roblox): A feature in the game Roblox that allows players to create gender-swapped versions of characters. Originally, R63 was one of the rules of the internet, stating that if something exists, there will be a gender-swapped version of it. However, over time, R63 became slang for softcore Roblox porn because R34 is censored but R63 isnt. Some people find R63 avatars on Roblox to be oversexualized.

Its worth noting that the first two definitions listed on Urban Dictionary are not related to the other meanings of R63 and are not appropriate for all audiences.