Size

In the first picture I see an elephant. Its colour is grey and it is enormous. Elephants are live in Africa and Asia. The African race is taller than the Asian race. In the picture in the middle I can see an ant. The ant is tiny, but in consideration of its size it is very strong. It is carrying a leaf which is much bigger than itself. In the right picture I see a short pencil. It is unusual because it has two tips. I can write with both ends.

It's  =  it is   (This will not be correct at the start of your second sentence.)   You are talking about something that belongs to the elephant or the ant so used "its".

Take care not to swap from 'you' to 'I' as you progress through your writing.  Either of them could be used in this writing but you need to make the choice.

On the first picture I see an elephant. It's colour is grey and it is enormous. Elephants are living in Africa and Asia. The african race ist taller than the asian race. On the picture in the middle you can see an ant. The ant is tiny, but in consideration of it's size it is very strong. It is carrying a leaf which is much bigger than itself. On the right picture I see a short pencil. It is unusual because it has two tips. You can write with both sides.

In the first picture I see a huge elephant. Its colour is grey. Elephants live in Arica and Asia. The African species is taller than the Asian species. In the second picture you can see an ant. The ant is tiny, but considering its size, it is very strong. It is carrying a leaf much bigger that itself. In the picture on the right, I see a short pencil. It is unusual because it has two tips. You can write with both ends.

Sehr gut gemacht! I changed the word race for species because race is mostly associated with humans.