G goes to the desired line number. For example, 25G will move the cursor to line 25. If you do not type a number, the cursor will go to the end of the file. O moves the cursor to the first character on the current line. M moves the cursor to the middle line of the screen.
L moves the cursor to the last line of the screen.
A 'word' is a sequence of characters between two spaces, or a sequence of special characters. You can type a number before the command to move the cursor the specified number of words. You can type a number before the command to move the cursor the specified number of words. J joins lines together. The line below the one with the cursor will be moved up to join the two lines.