I am trying to display a file from a SD card using the serial comunication with the PC.
Display it where?
I want to know if it can send a string that has strange characters as those (like →═ð) that you see in the .exe files when you open them with the notepad... Is it posible?
If "it" is the Arduino, then, yes it can send binary data to the serial port.
There may be any number of reasons why you get strange characters if you are not expecting them, or not getting them if you are. We'd need to see some code, and know what is actually on the SD card, and see what output you do get.