how do i know when a guy is flirting?!

Okay, I am very bad when it comes to talking to guys. Today at Costco this cutie talked me and my mom into getting direct tv. He kept saying stuff like ,"if you get it i will take you to breakfast or lunch " but he keeepptt saying it. I was hiding behind my mom for a little bit cuz i dont know how to act😂😂 he was so close to me too. I could literally turn my head and be within face inches from his face... and the eye contact had mee dyinggg😒😫