Why? Yes it is correct, but not by itself. “Una ensalada, por favor” is the Spanish for “A salad, please”
No, uno is strictly for counting: one, two three “Uno, dos, tres”
The minute a noun follows it you must use “una” for feminine nouns like “ensalada” and “un” for masculine nouns like “bocadillo”. “Una ensalada y un bocadillo, por favor.” or “Una ensalada y un sándwich, por favor.” of course that is not the phrase above.
Who are you answering? The answer at the top of the page is correct. The expression ”por favor” does mean “please”. https://dictionary.reverso.net/spanish-english/Por+favor
No, a missing or wrong letter will only be considered a typo if it does not make another word. “Pleas” is a different plural word.
Texting abbreviations are not accepted. Please use standard English.
Every word will have a recording that you can listen to, but not every instance of it will.
Are you asking if “A salad, please.” is correct ? Then it is. If you are asking if this is a question, then it is not.
“As a favor” would be “Como un favor” in Spanish; “Por favor” literally means “For favor”, but is actually used to mean “Please”
"Porfa" is a kind of short for "por favor", very informal/familiar or funny/childish, or for texting, maybe not used in/by all regions/ages.
Other variations may be porfi, porfis, plis. ☺