Clarify something for me please (run workout concepts)

Hello from the beautiful Kwajalein Atoll in the Republic of the Marshall Islands.  It's perpetual summer here, an outdoor type's paradise.  75-85 degrees year round... the only variable is how much wind and how much rain you get.  I live on the tiny island of Kwajalein, about 2200 miles south-west of Hawaii. 

Anyway, I am hoping someone here can help me out.  I'm ready to start a new training program and I am having trouble understanding some of the concepts in my plan.   On day 10, my run workout is this:

Run 40' - Warm up for at least 10' before the first stride. Run 8x30 left foot strikes - time should be between 19-21". In between each stride you will skip 40 times back to the start - take short rest and repeat. Cool-down with at least 5' easy jog (Zone 1).

And this is defined as:

Strides/Pickups - Short repeats at a 5K pace with recovery in-between.  Each 'repeat/stride' should be about 20-30 seconds long and allow for a full recovery in between.  Make sure you are properly warmed up-at least 10 minutes before the first.  You are looking to get in about 45 left OR right foot strikes per 30".  Multiply by 'two' for your RPM.  So 45 left foot strikes per 30 seconds will equal 90 RPM, a running cadence that is the most efficient.  You will typically be doing 4-10 repeats of 20-30" strides with a full recovery between sets (depending on the particular workout) by walking back to the starting point.

I definitely don't have a strong running background, so these terms are new to me.  I would be most grateful if someone could take the time to explain this to me in a simpler format.  What exactly does "5K pace" mean?  I've read over this several times and I *think* I get it, but I would feel more comfortable if someone put it in 3rd grade terms. 

Thanks very much,

-Alan