Is this the same sign as 'a lot' or 'much'?
Yes! This sign is frequently used for 'a lot,' 'much,' and 'plenty.' The core meaning is 'an abundant amount,' so it works perfectly for all of these English words depending on the context of your sentence.
How do I show that there is *too much* of something?
While 'plenty' is usually positive or neutral, if you want to show 'too much,' you would typically use a different sign where your dominant hand stacks on top of your non-dominant hand and moves upward, accompanied by a strained facial expression.
Do I need to mouth the word 'plenty' while signing?
You don't have to mouth the exact English word. Instead, focus on using your facial expressions to match the degree of abundance. You can slightly puff your cheeks or part your lips to emphasize a large quantity.