In The Ballad of the Green Berets, what does the first line mean?

One of the requirements of being a Green Beret (Army special forces in general, I believe) is being Airborne. Common insertion method for Green Berets would be paradropping.

Just like it says about the Green Berets it means just what it says. Men who jump are parachuting out of a plane. The Green Berets were trained to jump along with all the other training they received. The song doesn't say anything about snipers.

Ballad of two Brothers inner maximum John Q could desire to We combat 2 Wars there's a megastar bangled Banner Waving someplace Vietnam Blues upward thrust up FOr u.s. familiar SOldier u.s. Cried American Soldier

It references the fact that USSF [aka "Green Berets" are Paratroopers]

The term is paratroopers. Fully-trained soldiers inserted into action by air.

In Vietnam, the Green Berets were usually deployed from helicopters.

they are special ops group. they parachute, yes. though im sure some of them snipe too, jsut not while they are jumping.

type of sky,or air insertion isnt important, it is the fact no one knew where they were coming from, and they could appear anywhere

like the Navy Seals, men with green faces, coming from sea air or land

they are the paratroopers who parachute behind enemy lines to help setup our defenses. green barets becouse they wear green berets.

It means they ride around in fancy Learjets, sipping champagne.