This may be a particularly American photo but I am an American. . The yellow flag is known as the Gadsden flag. It depicts a coiled snake and it says "Don't Tread on Me. The black one says "Molon Labe "- which means "Come and Take it".
These two gentlemen were in attendance at an Overpasses for Impeachment rally during the obama administration. Local law enforcement did stop by during the protest but only to chit chat and answer questions from the protest organizers regarding banners.