Does modlitwa mean both a particular prayer and prayer in general? I put "prayer" sans article and it was wrong
Both, with 'prayer in general' being the more probable option here. So you'd use "Prayer" without an article for the general idea, and not "Praying"?
Sure, praying probably works better - should that also be accepted here? I didn't know if there was a different word for that. But prayer seems more abstract, not necessarily saying prayers, but thinking/meditating on a prayer or prayers, being in a state of prayer.
Well, technically its a gerund so it should be translated to "modlenie się" - the question is how grammatically strict we want to be, plus I really think that 'modlitwa' is better for many contexts, including this one.