The Wolfram Language has many matrix operations that support operations such as building, computing, and visualizing matrices. It also has a rich language for picking out and extracting parts of matrices.
Use Part to go to the first row and take the second element:
Or use the shorthand notation [[…]] for Part:
To take an entire column, you need to select all rows with All and specify the column:
To pick out a submatrix, you can use Span (;;). First, define a 4×5 matrix:
Extract the highlighted matrix by using Span (;;) to specify the relevant span of rows and columns: