Your English is just fine. No need to apologize.
About your son, if you don't already have any,
get some books from library with counting pages.
Ask the librarian to help you find some.
They will be on the shelves for toddlers . . . .
big oversized books.
Pictures and words and numbers . . .
for example: ONE APPLE with the words ONE and APPLE
and the digit 1 and a picture of an apple
TWO DUCKS with the words TWO and DUCKS and the digit 2
and a picture of two ducks
etc.
These generally go up to 10 and have brightly colored pictures.
There are lots of different kinds of these books.
Spend some time with him reading these together
until he can read them back to you.
He should understand the concept of 2,
whether it's a picture of two anythings or the digit 2
or 2 somethings in front of him, like 2 balls or 2 oranges, etc.
and the concept of each number: the digit, the word, the image.
When you're looking at a page with five horses,
point to the horses one at a time and say: one horse, 2 horses, etc.
or just one, two, three, four, five, as you point.
Have him say it after you do.
Point to each horse and tell him to say each number.
Does your son know the names of numbers in your native language?
If so, you can make up some pages yourself,
with both words with pictures . . . .
each number word written in both languages.
He'll be just fine. He'll probably pick this up very quickly.
You can add practice, for example, in the kitchen while you're cooking.
How many carrots? How many spoons? etc.
When he gets past counting to 10,
you can ask him how many books on the shelf,
how many houses on our street?
etc.
Good luck.