友 is two hands (the radical 又 means 'hand') reaching the same way, side by side — two hands working together, clasped in the same direction. That image of joined hands is friendship.
友 pairs with 朋 for 朋友 (friend), and stands for friendliness itself: 友好 (friendly), 友谊 (friendship), 友爱 (fraternal love). In compounds it labels companions: 网友 (online friend), 笔友 (pen pal), 校友 (alumnus). A warm, sociable character.
Two hands reaching the same way, clasped — FRIENDSHIP.
友 names all kinds of companions: 网友 (online friend), 笔友 (pen pal), 校友 (schoolmate/alumnus), 战友 (comrade-in-arms). Add 友 and you've made a friend.