To make music, we need to play some notes for a longer time and some for a shorter time. The time that a note takes is called its value, and we draw notes to indicate the value:

𝅝 A whole note is usually the longest note you will see. Each whole note gets four beats. Count it as “1-2-3-4”.
𝅗𝅥𝅗𝅥 There are two half notes in a whole note. Each half note gets two beats: “1-2 1-2”.
𝅘𝅥𝅘𝅥𝅘𝅥𝅘𝅥 There are four quarter notes in a whole note. Each quarter note gets one beat. Count it as “1 1 1 1”.