Of late is a slightly fancy way to say "lately." If you've gone out to the movies six times in the last week, you could say you've seen a lot of films of late.
The adverb of late can be used anywhere you'd use words like recently or these days. If you've been spending too much time online of late you might have a headache and the realization that you've been putting off starting your homework. If you've been thinking of late about volunteering at a food pantry, you've spent some recent time considering this option.