DATEVALUE(LEFT(F4,FIND(",",F4,FIND(",",F4)+1)-1))+TIMEVALUE(RIGHT(F4,LEN(F4)-FIND(",",F4,FIND(",",F4)+1)-1))
The above-highlighted components in common are intended to identify the position of the first comma, which in the standard date string separates the day from the time. The reason this is important is because, by adding 1 to it, we then find the first character *after* the first comma, which is important...
DATEVALUE(LEFT(F4,FIND(",",F4,FIND(",",F4)+1)-1))+TIMEVALUE(RIGHT(F4,LEN(F4)-FIND(",",F4,FIND(",",F4)+1)-1))
...in order to find the *second* comma, by starting our outer FIND from that point and working onward. This wouldn't be necessary if we could specify what "number" character we wished to find or if we could start by searching from the right leftwards, but I digress. Anywho, this comma separates the year from the time, and is thus very useful to finding these two separate components.
Now, then, we can study the rest in two sections. Studying the first (DATEVALUE) part specifically:
DATEVALUE(LEFT(F4,FIND(",",F4,FIND(",",F4)+1)-1))
We simply take all the characters to the left of that second comma using the LEFT function, consulting the entire string (contained at F4) and stretching out to the second comma, minus one character to remove the comma itself. This gives us a very simple string containing something like "May 24, 2017", which the DATEVALUE can understand perfectly well in most English region/language settings. Google warns about how certain formats may not work in all locales, so it may be worth noting in case you're running in, say, Chinese where "May" is not a recognized month, but "五月" or "5月" would be. I'm personally not sure; I didn't play around with alternate locales.
Now, moving on to TIMEVALUE, it's constructed very similarly...
TIMEVALUE(RIGHT(F4,LEN(F4)-FIND(",",F4,FIND(",",F4)+1)-1))
...but this bit is a mite more complicated. That's because if you skip ahead a bit, you'll see we're grabbing everything to the RIGHT(), now. What we need is therefore the number of characters left over after you remove what's to the left. Hence, we grab the length of the entire string with LEN, chop off the bits that include the comma, and since this still leaves a single space character left-over (because the entire delineator is actually a two-character ", " comma-space, and not just the comma), we chop off an extra one character to remove the space. Very fussy, very ad-hoc, very typical. From there, it's very straightforward...
TIMEVALUE(RIGHT(F4,LEN(F4)-FIND(",",F4,FIND(",",F4)+1)-1))
Just grab the stuff to the right of that comma, excluding all the fiddly bits, which returns something along the lines of "11:56:16 pm", and dump it straight into the TIMEVALUE function.
Finally, we add it all together, and out pops some lovely number like "42879.99741". This is, as mentioned above, Excel's lovely standard format for dates. If it looks like no date you've ever seen, you would be right; Excel uses a serial date format that runs based on the number of days since 1900-01-00, where that date itself is number "1", give or take a day due to a compatibility requirement with a predecessor that had minor legacy bug that incorrectly identified 1900 as a leap year since it was divisible by 4 (it's a century year not divisible by 400, so it's not). Simply setting the format to identify the cell containing that number as a Datetime is enough to get it to display nicely and properly in human-understandable terms, while still permitting all the lovely standard
Excel Google Docs functions to work on it. Oh, and if you think it looks like any other example of epoch time that you've seen before (say, Unix epoch time, which uses 1970-01-01 as its epoch and seconds for its increment), congrats, you're a leg up on me back when I first started learning how to code-monkey inside Excel.