You can find the Matrix field in the Advanced tab:

You can enter the field name and list of values to column and rows (one per line):

On the Matrix field editing page you can:

1. Change the field name.

2. Add new rows or columns using the "+" icon.

3. Delete existing rows and columns using the "trash"  icon.

4. Change the rows and columns order using the "arrow" icon.

5. Specify the cell width.

6. Enable or disable the "Show modal form for filling the matrix" option.

7. Enter the instructions for users.

On the Validation tab you can:

Enable the "Can't be blank" and "Check data uniqueness in this column" options.

An example of the Matrix filling using the modal form:

Matrix in the "Records" menu: