It's like 'er'. "Schwa is a very short neutral vowel sound, and like all vowels, its precise quality varies depending on the adjacent consonants. In most varieties of English, schwa mostly occurs in unstressed syllables (exceptions include BrE concerted), but in New Zealand English and South African English the high front lax vowel (as in the word bit) has shifted open and back to sound like schwa, and these dialects include both stressed and unstressed schwas. In General American, schwa is one of the two vowel sounds that can be rhotacized. This sound is used in words with unstressed "er" syllables, such as dinner."

It depends on your native language but for people who speak Spanish, Italian, French or even German where vowels are very well pronounced, my advice is ALMOST FORGET TO PRONOUNCE THE SCHWA especially if it's in an unstressed syllable. Even if you don't try to pronounce it, some sound will appear. It will be almost enough.

Examples:

LESSON pronounce something similar to LESSN

PENCIL pronounce something similar to PENSL

RECORD similar to RECRD

As for "away" and "America" the first "a" of the two words are schwa and pronounced the same, a very obscure sound almost inexistent.

I think they're talking about the first 'a' in 'away.' Because this sound is only found in unstressed syllables in most American dialects, many Americans have a hard time producing it in isolation. Some may perceive it as identical to the 'u' in 'but,' but this is not usually true.