How many moves ahead do you guys usually think? What does it mean exactly?

One

Couldn't agree more. Knowing when and what to calculate is incredibly important. Also, being good at visualising the board and seeing several moves deep is worthless if you are bad at tactics. It is pointless to calculate 5 moves ahead if you will be missing all the tactics that will occur just 2 moves deep.

Calculation is one tool... in other words it's not the only tool.

In positions where it's useful (and possible) of course GMs will look 10 or 20 or etc moves ahead. If you can play a blindfold game then you can "look" a whole game ahead, and players far below GM do that.

The strength of a player's ability to calculate isn't depth, but efficiency and accuracy. I might spend 20 minutes trying to figure out a move that a GM would dismiss as incorrect right away... and this implies that even when I'm calculating the correct line for the correct reasons, I'll be distracted by bad moves that a GM wont waste time on.

And this is the kernel of truth in Capablanca's quote "I only see 1 move ahead, but it is the best move." In many positions all you need is the correct evaluation and the correct idea.

300 rated players see 3-4 moves ahead ? ya kiddin right ?

depending on time left and position, between 5-8 moves at most. normally around 3-4

1-10 really. However, when tactically correct, this is enough to play best moves. 🙂♟️

Better late than never.