The most common meter in music is 4/4. It’s so common that its other name is common time and the two numbers in the time signature are often replaced by the letter C.
In 4/4, the stacked numbers tell you that each measure contains four quarter note beats. So, to count 4/4 meter, each time you tap the beat, you’re tapping the equivalent of one-quarter note.
The 4/4 time signature is the most common time signature in rock, blues, country, funk, and pop, that’s why it receives the name Common Time.