Hi AlexManu,
@SearchTerm is the parameter name whose value will be passed from TextBox.
When you will enter value in TextBox, same value will be checked with multiple columns.
If it matches in any column then the result will be displayed in the DataGridView.
By default the DataGridView will show all records. As soon as user starts to type in the TextBox, the records will be searched in multiple Columns.
For more details refer below article.