You can but make sure you link to relevant sites only, ie. sites whose subject matter is the same as the hub you're linking from. Google likes links that keep readers 'moving forward' in their search. If the link appears to be to an unrelated website, Google will see that as a step backward for your readers and so will penalise your hub by ranking it lower in search rankings. Attribution links to images you use are included in this, so if your attribution link doesn't link to a related site, avoid giving attribution if it's not required or avoid using an image that requires attribution if you can.
It's OK to include more than one relevant link. Like keywords, links should be proportionate to the amount of text in your hub. I would include one link for every 200 words or so.