Mercury will be retrograde from July 7 - August 1, 2019. A retrograde planet appears to go backward in the sky. This is an optical illusion, but it has symbolic meaning. During a retrograde phase, the planet's energy is experienced in a more internal, and more obsessive way.
With Mercury, the tendency is for the intellect, which is Mercury's domain, to work overtime. During this period, we tend to do more mental processing. Communication can get complicated, so it is not a great time for signing important agreements. However, it is a great time for improving things that are related to information. Editing, studying, memorizing, and working on improving communication, are all supported by this period.
Mercury begins it's retrograde motion in Pushya nakshatra. Pushya is ruled by Brihaspati, the guru of the gods, so this is a good time for listening to feedback from teachers or advisors and working to make improvements. On the other hand, if your teacher or advisor is not serving you well, then this can be a time for moving on.
The shakti of Pushya nakshatra is the power to create spiritual energy, so this is a good period for any type of spiritual practice, but especially for taking classes that have a spiritual, or at least an emotionally uplifting, quality.
In general, Mercury's retrograde period is good for making improvements. It's not the best time to begin new things, but it is good for fixing or improving things from the past. It's like an airplane in a holding pattern. It's not time to make a landing yet, so just relax, clean up your seat area, give your empty cup to the flight attendant, and stow your things in your carry-on bag. Be patient, you'll be landing soon, and you'll be ready to start your new adventure.