So i got ArcMap Basic and i want to bring my 100000 rows thick excel table to GIS.

In overall 8 columns are my 4 coordinates: coordinate 1 lat, coordinate 1 long, coordinate 2 lat ....

would be easy to average the 4 coordinates and just show for every row one point.

But i need to present every row as a polygon. A polygon square with 4 vertex (one for every coordinate). Like a footprint.

Does anyone have an idea?

Here's a basic version of a script that might work for you:

First I created the output polygon feature class "csv_points_poly" in my scratch GDB with an additional "ID" field.

Then assuming your XLS/CSV file looks something like this:

You can use numpy to make an array of your data, which you can iterate to build a polygon for each row.