Student or Learner
The outline of the ‘red cross’ in green and orange as a connecting lines symbolise association and the four small circles on each corner denote the network of the people promoting the best healthcare in the community and country. The blue color mostly associated with medical industry represents commitment for promoting healthier Maharashtra
The verb symbolise refers to the outline. Since there is only one outline, you must write the verb as symbolises. If you removed the phrase about the red cross, your sentence would read "the outline symbolises association."
Also, you need to add articles in front of some of the nouns. For example: the blue color...associated with the medical industry. The same is true for Maharashtra: promoting a healthier Maharashtra.
You also need to add some commas. Your final paragraph should read:
"The outline of the 'red cross' in green and orange as connecting lines symbolises association, and the four small circles on each corner denote the network of people promoting the best healthcare in the community and country. The blue color, mostly associated with the medical industry, represents a commitment to promoting a healthier Maharashtra."
I am not certain if you need to include 'red cross' in quotation marks. I hope this helps you.