If you find yourself writing a phrase over and over again, you can simplify that by creating a Global Merge Tag. Just go to:
Left Side Menu Bar > More Features > Tags > Add or Edit Global Merge Tags
Under "Global Merge Tags" page, click "Add New Global Merge Tag".
After clicking it, there will be a pop up window where you can edit all the details about the new global merge tag that you will be creating. Once you're done, simply click "Save".
Here's an example on how they work. I created a Global Merge Tag that and placed it in the email.
This is how it will appear before you send it. But after it is sent you will receive what the merge tag is supposed to say.
Note: Global merge tags will only work in emails as of now, not SMS or push messages.