It looks like you copied that command from a site that prettifies punctuation. Notice how the dash before lastwake there isn't a normal dash like you get from hitting the - key. (The program sees the different character and thinks it's part of a different and unknown parameter.)
The character in your command is slightly wider than the normal dash. On the left here is a normal dash, and on the right is your dash (an en dash):
- –
If you type out the dash version of the command or copy powercfg -lastwake into your command prompt, it will function as normal.