"I have some money."
Translation:Tengo algo de dinero.
Alguno can act as a pronoun or an adjective. As an adjective before the noun, it means some/any (none in particular) of a larger set of things/options, 'Quiero algunos libros' -> 'I want some books'. However, when 'algo de' precedes a noun, it indicates just a (small) fraction of a whole, 'sé algo de español' -> 'I know some (or a little bit of) Spanish'. In this exercise, 'algo de dinero' works better than 'algún dinero' as I have a small fraction of something (money).
Here is a good article on algo vs alguno: http://www.spanishdict.com/answers/9070/alguno-vs-algo-adjective-or-pronoun-or-adverb-