Question: For some reason I feel its overkilling on the use of article(the) here, 

> 
> To refine the results, please use the categories on the left
> 
> 
> 

Can someone help?

Answer: 
In my opinion, the phrases: 

1. 'the results' - refers to the specific results that will be refined;
2. 'the categories', - refers to the specific (provided) categories; and,
3. 'the left' - refers to the specific side (i.e., not the right side, not the top, etc.).

So, I don't think the word 'the' is overused.
As a native speaker, I can definitely say 'the' is not overused in this sentence. The is one of the most common words in the English language, so often in fact you might use the word 'the' over 5,000 times *in one day.*