Why are there three words if there is no difference? In English there are often words that mean the same, but have subtle differences (eg: request, ask and inquire). Are divka and devce and holka used in particular situations or ages? Are they originally from different dialects?
There are small differences in style/register:
Dívka: formal, standard
Děvče: old-fashioned, bookish, but also cute
Holka: informal, colloquial
An official form would always use "dívka", while in everyday speech "holka" would be the most common. Otherwise they can mostly be used interchangeably. There are also other forms, especially diminutives like "dívenka", "děvenka", "děvečka", "holčička", each with another shade of nuance.
kacenka9, could you give some examples of certain kinds of social groups [or region, social setting, other variables..] that where the use of a synonym for "girl" is most common in [Scenario 1: holka most common], [Scenario 2: devce most common], [Scenario 3: divka most common], etc...?
That changes with time. Start here https://forum.duolingo.com/comment/27749621/So-many-different-ways-of-saying-things-hoch-kluk-chlapec Holka is the most informal, but the possible derogatory meaning is probably lost. Devce and divka are really very similar to me, I'd say it is just personal preference.
When it comes to regional differences, you would be looking for dialectal words, which are different fro those presented here (děuče, děvčica, galánka, galán, šohaj,...).
"špatný" means both "bad" and "wrong", the meaning is normally clear from the context. In case it's not clear, it's possible to use "chybný" (from "chyba" - "mistake") for "wrong" or "nesprávný" for "incorrect".
On the other hand, "bad" can also mean "evil" in English, but not so much in Czech, where the word "zlý" would be used to express that. So as you can see, there are overlaps. Words in different languages don't fit each other exactly in all their meanings.
Here: https://dictionary.cambridge.org/dictionary/english/bad (see the third definition)
Or what about the Big Bad Wolf in Little Red Riding Hood? He most definitely can't be named "špatný" in Czech or even "nezbedný/zlobivý" (naughty), but only "zlý" (evil) :)
"Girl" is an English word. "La chica" is feminine in Spanish. "En flicka" is common gender in Swedish. "Tyttö" is genderless in Finnish. "Das Mädchen" is neuter in German. "Děvče" is neuter in Czech, but "holka" and "dívka" are both feminine in Czech and they mean "girl", too.