What in particular is not clear to you in these snippets?

In the first part, $6 contains whatever was matched by the 6th set of parens in the previous regex match (basically, everything in the log entry following the time stamp string), $ts is the "seconds since the epoch" time-stamp that corresponds to the matched time stamp string in the log entry, and the if statement returns true on any case-insensitive match of a "word" token from the log entry to the target $word.

The second part is a loop over hash keys that are being sorted numerically. The first line in the loop creates an array ref containing the list of values returned by localtime, and then uses selected values from that array to create a string that is formatted the same way as the original log entry time stamp string.