Can someone on these two question i don't get this at all i'm really confused

1: explain how dominant and recessive alleles for the trait of stem height determine weather a pea plant will be tall or short.

2: can a short pea plant ever be a hybrid for the trait stem height? why or why not.

Alleles are letters that represent dominant and recessive traits.

A capital letter represents a dominant trait
A lowercase letter represents a recessive trait.

Dominant traits over shadow the recessive ones. This is known as complete dominance.

Referring to your questions let's us the alleles HH, Hh, and hh for the height of the pea plants.

But what do those letters mean?

HH = homozygous dominant (Tall)
Homo means same.

hh = homozygous recessive (Short)

Now this is different: here's Hh.
There's a capital AND lowercase letter.
This means that the plant carries the gene for tall and short plants, and can pass on either trait to the offspring.

BUT the dominant always over shadows the recessive. So Hh is a tall plant.

Hh = heterozygous (hybrid) (Tall)
You can interpret hetero meaning different.

Now I hope you're with me!

For question two it asks if a short plant can ever be a hybrid.
Referring to what I just said, that answer would be no.
Because there is no dominant trait to over shadow the recessive.

And short plants have the hh alleles, and they are homozygous NOT heterozygous (hybrid).

I hope this helps, and makes sense! If you have any questions please let me know. Genetics can be confusing.

Being Tall is a Dominant trait, even if the alleles are Tt (heterozygous), the pea plant would be tall. But if the alleles are tt (homozygous recessive) the pea plant would be short. TT would mean homozygous dominant are result in a pure tall pea plant. 

The answer is observations and interpreting.