git log uses your configured pager to display one screen of information at a time.
The default pager on Unix-based systems nowadays is less and this is probably also the pager on your system. I guess you are using Git Bash which is just a bunch of Linux programs ported to work on Windows.
less displays a screen of information and on the last line of the terminal window it displays the : prompt, waiting for a command. It has several commands you can learn about if you press h at the prompt.
The most used less commands are:
f or <space> to display the next screen (f comes from "Forward");
b to display the previous screen (b comes from "Backward");
/ followed by a regular expression and enter to search for matching substrings in the input data, starting with the displayed screen (search forward);
? followed by a regular expression and enter to search backward;
h to display the help (the list of commands);
q to quit.
Most commands have two or more keys assigned. I listed above only on key which is also the easiest to type.
You can use the less commands when you read its help (it is more than one screen).
If i type CTRL+C 2 times i can see the '$' sign but the text is still gone.
On quit, less restores the screen in the status it found it when it started.
In order to use a different pager program (for all Git commands that require one) you can set it in the Git config:
git config core.pager /bin/more
Replace /bin/more in the command above with the full path of you favorite pager program.