How do I make meta description automatic?

I watched yahoo finance share quotes and saw that the meta tilte is changing according to the share current price. how they are making it? can i make it as well?

Those are dynamically generated according to the real-time share prices

Hello, Well there no such automatic tool or any method which generates your meta description fast because as per google guidelines meta tags should have the targeted keywords in it and also follow the character guidelines. If automatic meta tags will be used it will not be optimized by google and your website will not rank. So try to create meta tags of your own.

Google will automatically generate a description using content from your page based on the search query, if you do not declare an explicit meta descripton. Often they will bypass your meta description anyway and use theirs.
Many argue it's better not to declare a meta description on some pages. The best practice is to use & write a meta description to optimize for click through in the SERP.. although clicks are mostly driven by position.