I was looking for help on the Englishpage.com website on its Modal Verb Tuturial on the modal verb 'can' and seem to have found that they use categories to explain the various uses of 'can'. One category is 'can' as 'opportunity' -- and gave this example:

I have some free time. I can help her now.

Now, if you look at the two sentences together and look for the overall context, the 'opportunity' part comes out clearly, but if you exclude the first sentence and only look at the second sentence, which is 'I can help her now', it looks like it is talking about 'ability'. Should I look at the overall context when following up on the recommendations, if that is what can be called, or focus on a single sentence, which might render a different interpretation of the category or render a different impression of the category indicated?

I seem to have similar confusion over some other categories in regard to modals 'can' and 'could' there if I am not mistaken too
Is it really very helpful to you to divide the uses of words like can and could into groupings like 'ability', 'possibility', 'capability', 'opportunity', 'eventuality', 'potentiality', and so on and so forth? The differences between these are very subtle, even to native speakers. And often two or more of these concepts are involved within the same sentence.
I've noticed a lot of posts along similar lines, and I can't imagine what is helpful about it. Emotion: smile
>And often two or more of these concepts are involved within the same sentence.
CJ's right. Pointless work to a large extent. Too much overlap.
Start reading the great writers and try to have ONE explanation for each of their uses and you'll be fine.