ein Bißchen Deutsch

BTW, this should be written as:

ein bisschen Deutsch

We switched from ß to ss in all words with a preceding short vowel in 1996: https://de.wikipedia.org/wiki/Reform_der_deutschen_Rechtschreibung_von_1996
So, it's "Fuß" and "Maß", because those are pronounced with a long vowel, but then "Fass" and "muss" and "Biss", because those are pronounced with a short vowel.

And in this case, "bisschen" is spelled with a small "b" for reasons that I'm not entirely sure are logical. 😅
It would be spelled with a capital letter, if "Bisschen" was a unit of measurement here (i.e. a small bite), like a "Liter" is.
But because it was used so much and without really referring to a specific measurement, it eventually began being spelled lowercase, similar to "wenig" or "etwas" ("ein wenig Deutsch", "etwas Deutsch"). Apparently, this kind of word is called an "Indefinitpronomen".

https://de.wiktionary.org/wiki/bisschen
vs.
https://de.wiktionary.org/wiki/Bisschen (much rarer)