Watts is a unit of work (like "wattage") - not an acronym.
FTP is Functional Threshold Power (or "1 Hour power")
LT is Lactate Threshold
BPM is Beats per Min (HR, or Heart Rate)
KG is kilograms. 2.2 lbs = 1 kg
TAXC is... no idea. Either a type of trainer or those water bottle holders made of carbon.
HR is Heart Rate
TSS is Traning Stress Score
ATL is Hotlanta, I mean Acute Training Load
CTL is Chronic Training Load
Peaking? I'll let you figure that one out.
Keeping elbows sharp must mean to keep them bent - a common newb mistake is to keep them locked straight.
For all the TSS/ATL/CTL stuff see
here.