4x4 aluminum sheet

What does 4x4 aluminum sheet metal mean?

4'x 4' also called 48“x 48”, because this is an imperial measure. The single quote ' refers to the foot. 4' and A' respectively indicate 4 foot and 4 foot, 1 foot=304.8 mm, 4'=1219 mm

4'x4' aluminum sheet metal indicates the width of aluminum sheet plate × length = 4 foot × 4 foot = 1219mm × 1219mm.