In other words, it's taking a picture of whatever is showing on your computer, mobile, or tablet screen at the time.
N'ikwu ya n'ụzọ ọzọ, ọ bụ ụzọ nke iwepụta foto ma ọ bụ foto nke ihe ọ bụla na-egosi na kọmputa gị, mobile ma ọ bụ mbadamba ihuenyo n'oge ahụ.