SEO stands for Search Engine Optimization. It's a technique which helps webmasters to optimize their business website so that the potential customers can find them on the search engine, which means optimizing the website in a manner that when a user searches with relevant keywords related to your website, your website will show in top results of SERP (Search Engine Result Page).
SEO has two main elements: On-Page SEO and Off-Page SEO.
First, let's learn about On-page SEO:
On-Page SEO - is optimizing the content of your website on your own website. Optimizing your Website or web page in order to rank higher. There are different factors that can improve ranking; one of them is 'Content' - relevant content plays a very important role in ranking on the search engine.
For that, you need to optimize your Website UI, Content, Title Tag, Meta Description, URL (Domain Name, Subdirectory), Header Tags, Keywords (both Short Tail Keyword and Long Tail Keywords), Image Alt Text, Anchor Text, etc.
Off-Page SEO - is when you optimize your content on other websites. There are so many ways to optimize your content on other websites, one of them is creating backlinks on other websites. Optimizing content on other websites with link building, guest posting, etc in order to rank higher. Here also relevant Content plays an important role in the ranking.
For that, you need to optimize yours in such a way that you will get traffic from those websites to your website. The core of Off-Page SEO is backlinks. Backlinks are those links that are coming from your someone else's website to your website. Search Engine gives more priority to a backlink if the link is coming from a good high DA website.
Now after learning what is SEO and how to improve SEO, a question comes in your mind :
First, let's learn about what is Ranking? The ranking is When you/someone searches for a query, on Search Engine and Google will show the most relevant answer to your query and rank them in order(most relevant to least relevant), which is called Ranking.
How to rank on Google? There are two ways to rank higher on Google,
Organic - which is Search Engine Optimization. As I mentioned above how to optimize SEO.
Paid - which is Search Engine Marketing. For this, you can run Advertisements on Google, for that you need to create Google AdWords Account and run ads on Google.
It's up to you what you want, if you are looking for instant traffic to your website then Google Ads will help you, but paid/adverting traffic will not help you in long terms, you need to do SEO. SEO is long prosses but it will help you in the long term.*Ranking depends upon different factors and requires a proper strategy.