The 12 times table lists the multiples of 12: 12 × 1 = 12, 12 × 2 = 24, … 12 × 12 = 144. "12x" usually refers to this multiplication table.
"12x" can mean 12 times a variable, but most people searching it want the 12 times table: 12 × 1 = 12, 12 × 2 = 24, … 12 × 12 = 144.
Learn the multiples of 12 from 12 × 1 = 12 up to 12 × 12 = 144. Count up by 12 each time, or drill yourself with the table above.