How to describe the languages of these regular expressions in plain English?
The first regular expression captures all strings over $\{0,1\}$ not containing two consecutive 1s. It is not hard to check that any string in the language of the given regular expression has this property, and with some more work you can show the converse.

The second regular expression captures all strings over $\{a,b\}$ containing $aaa$ as a (consecutive) substring, as you also noticed.

The third regular expression captures all strings over $\{a,b\}$ not containing $bba$ as a (consecutive) substring, though this perhaps requires some verification.