On the right
This has a very simple explanation: The actions you're going to apply are based on an object. Thus, for western languages such as in your example, it's natural that you read from left to right. If you have the actions before the object.... what are you going to act over? You still didn't see the object to act upon!
There are 2 additional concerns on your question
- Checkbox: should be on the left side, just like you have it now
- Dropdown: It's very important to define what do you have in your dropdown. IF these are actions that affect the object itself, and they're more than 3, quite probably you'll need to use only a dropdown, and all the actions should be contained inside it.
However, if the actions contained in the dropdown are unrelated to the specific object, it shouldn't even be there and you should try another option.
While not strictly related to dropdowns, a good example of guidelines for this is Material Floating Action Button since the same principles apply to your case
Avoid using floating action buttons for minor and destructive actions,
including the following:
Archive or Trash
Alerts or errors
Limited tasks like cutting text
Controls that should be in a toolbar, like volume control or changing a font color
Don’t include unrelated or confusing actions.
In the end
test, test, test