How to make a realtime like counter?

You can use the Roblox API to get data on the game with an HTTP request. I don't have any example code of that, but I know that this is what API request you need

You can also see it on the docs

In short, what you will have to do is use HttpService to make a web request to get the likes and dislikes in game. There are tutorials on other http requests that can teach you how to do this, just search up "Roblox how to use roblox api with httpservice" or something like that.