It’s very easy to filter in built list view web part OR SPList in UI.
Below query string is filter list.
?FilterField1=[Internal Field Name]&FilterValue1=[Value of Filter Field]
For more understanding let’s take one example.
Here I created one sample List which contains Title, Date, City and Country Columns as per below.
Now I want to filter on Country Column so query string looks like
?FilterField1=Country&FilterValue1=USA