Google Tag Manager - Overview of Data Layer

Indian Tech Guys are CHANGING world.

Hi, I am new to Google Tag Manager. Today I captured an event from clicking a text hyperlink on my blog to an external website, which I saw in G Analytics in the real time mode. I didn't make any data layer first. So, basically, my question is, what is the difference between an event captured without a data layer and then also with a data layer?

How can we get the count of a particular link clicked in a table into Data Studio?