First make a layer for the timer, and set the parallax to 0 so that it will not move when the view does. Position your text where you want to show the time measure (score.) The dotted line represents the border of the players view, so use that to reference where you want the timer to always stay. Also add a "keyboard" object to your project so you can map the spacebar action later
In the event sheet make a variable "score". Make an event with a condition of every x seconds, and use the amount of seconds you want to pass before another point is added to the score. make another condition for the object to not be touching (overlapping) whatever object you want it to pause et. Make an action for your text box that will display the score and set it to "add to variable" action. Select the amount you want the score to change by with each second passed.
every 1 second | add +1 to "score"
is not overlapping object |
Make a second event that is "every tick", and give that an action using the text box you made for score set the text to "score".
every tick | set text to "score"
make a third event with the keyboard condition "on pressed" and select spacebar as the button that should be pressed. give the event an action of setting the variable "score" to 0. This will make it so that whenever you press spacebar you will have the score reset to 0