This is not the vietnam war as the other entry states in the "the guess who" lyrics. It is clearly a song about a jaded ex-lover, and a how he has no time for her
Killing Floor is the grounds they butcher animals on. Metaphorically it just means place of turmoil, possibly their apartment.
see: Killing Floor
"No time for a summer friend, no time for the love you send, seasons change and so did I, you need not wonder why...no time left for you.. no time for the killing floor..."