Can someone explain semantic seo?

A cheap way to see it in practice: search your main keyword and open the People also ask box. Those are related questions Google already connects to the topic. Answer the relevant ones properly on the page and you're doing semantic SEO without needing a tool. Schema markup helps a little too, since it states what things are (a product, a person, a recipe) instead of leaving Google to work it out.

Basically writing for the topic, not for one keyword. Google understands meaning and related concepts now, so a page about running shoes that also covers cushioning, pronation, sizing and how long they last reads as more complete than one that repeats running shoes forty times. In practice: cover the questions people actually ask around the subject, and link related pages on your site together so they form a cluster.