How does pico-8 export games isn't it a program itself is there a complier and assembler inside pico-8 i understand the html javascript part it creates a little emulator with cart data embedded but i could not understand how it turns them into binaries

I'm not entirely clear on what you're asking, but it's basically the same thing as with the JavaScript export. It's exporting a copy of the PICO-8 interpreter wrapped around the game. That's pretty much it I think.

i mean how can it give output like .exe you need compilers, assemblers to create that like gcc for example

There is not a compiler inside PICO-8. It's much simpler than that. Notice how when you export something to a .bin it's nearly instantaneous? That's because it's just bundled with premade executables for Linux/macOS/Windows and then it puts those in a folder with a data.pod file which I think is just the cartridge (and possibly other platform-independent data?) and the executable knows to load that data.pod file.

thanks