Can i make a "export save to a file" for my game?

Can i put in my game a system that let me save the game in a external file and load that external file to open the save? like a "save state file" in emulators

What platform are you targeting? In NWJS export for desktops you can write data to files and read from files. In a browser game you will have to prompt user to download the file to their computer. In a mobile game this may not be possible at all.

i'm going to use the nwjs, do you know if there's any way that he can make a save file and read?

Here is the bare minimum. If you call these functions, the game will be saved to or loaded from the specified file:

You can learn how to open a file/folder selection dialog in the documentation:

construct.net/en/make-games/manuals/construct-3/plugin-reference/nw-js

can you send me the print equivalent to the construct 2 instead of construct 3?

You don't need to use the functions, just copy actions, they are the same in C2.

thanks :)