You have a worksheet and you want to show only a limited area to users. Say you want them to see only A1:G50 and remaining you don't want to show them.
Use following steps –
1. Click column H so that entire column is selected. Now CTRL+SHIFT+Right Arrow key so that all columns will get selected right of column H. Now right click and hit Hide. Now all columns right of G will be hidden.
2. Similarly click row 51 so that entire row 51 is selected. Now CTRL+SHIFT+Down Arrow key so that all rows starting 50 are selected. Now right click and hit Hide. Now all rows starting 51 will be hidden.
Using above technique, I have hidden entire area except A1:G20 in below screen shot.
3. If you want to make sure that nobody ever is able to unhide these hidden rows / columns, protect the sheet with password after making the visible area not locked. To make visible area unlocked, select the visible area > Right Click > Format Cells > Protection, here uncheck the Locked Box.