Why decreasing my website searches, impressions, and clicks?

Hi friends, 

I am working on a product-based B2B WordPress website in the electronic category. I am doing SEO on-page and off-page also from 2 years. But in the last 2-3 months my keywords ranking decreasing as well as search impressions, clicks, Positions continue. I don't understand what is happening?

If any solution you have then let me know.

Thanks in advance.