Meaning: Coming after all others in time or order; final.
For example, if signing LAST WEEKEND in this context, it means the final one, not the previous weekend. No more weekends after this last one. Another example, "This is the last book we have in stock."
For the LAST as in the previous one, sign LAST (PAST) this way.
Meaning: (of a process, activity, or state of things) continue for a specified period of time. E.g. lasted for 25 minutes.
First 100 words.
As you feel more comfortable with the first few hundreds of ASL signs, progress further with your vocabulary and learn signing more.