'button on the left' is a correct and usable phrase in written English.
For example, you could use it in a sentence such as: "Please press the button on the left to continue."
Jaguar's voice-recognition system has one activation button on the left side of the steering-wheel hub.
A dial and button on the left edge of the unit let you perform many tasks with one hand.
The reset button on the left lets you undo all of your changes if you need to go back.
By clicking the play button on the left top corner, training starts from the initial state.
There's a power button on the left side and volume buttons on the right.
You can also reach the advanced search features using the Search GrantsNet button on the left navigation bar.
All you have to do is fire up iTunes and hit the Genius Mixes button on the left taskbar.
Xiaomi has also snuck an 'AI button' on the left side of the phone, a first for the company.
It links to the annotation view by clicking on the Annotated Probe List button on the left panel.
