There is a typo in the the lesson "To Grab Space or to Not Grab Space?". Before your first move, under the dotted line in the commentary section on the right (don't know what it's called), it says "and being board...", which should be changed to "bored".
The pun, also called paronomasia, is a form of word play which suggests two or more meanings, by exploiting multiple meanings of words, or of similar-sounding words, for an intended humorous or rhetorical effect. These ambiguities can arise from the intentional use and abuse of homophonic, homographic, metonymic, or metaphorical language. A pun differs from a malapropism in that a malapropism uses an incorrect expression that alludes to another (usually correct) expression, but a pun uses a correct expression that alludes to another (sometimes correct but more often absurdly humorous) expression. Henri Bergson defined a pun as a sentence or utterance in which "two different sets of ideas are expressed, and we are confronted with only one series of words". Puns may be regarded as in-jokes or idiomatic constructions, given that their usage and meaning are entirely local to a particular language and its culture. For example, camping is intense (in tents).
What is that for?
He's implying it's a pun.