The title of your post implys that you have obtained a Part 107 Certification and you wish to conduct a flight in the area that your arrow point is indicating, under Part 107 Rules and Regulations.
If that is true, lets take this one thing at a time.
First of all, for this conversation, there are no classes of airports. An airport is an airport. There are only Classes of Airspace.
An airport will be located with-in one Class of Airspace or another, and can be enclosed with-in multiple Classes of Airspace, depending on hours of operation and/or types of approaches into the airport.
In the case of Ocean Reef Club Airport, it is surrounded by Class E airspace. The Class E bottom is at 700 AGL & the top is at 14,500 MSL.
From 699" AGL and below, with-in the Class E boundry surrounding the airport, the Airspace is Class G - Uncontrolled.
The 06 is the MEF for that quadrant. The MEF is the Maximum Elevation Figure, and represents the height of the highest natural or man-made feature with-in the quadrant. A quadrant is 30 Minutes of Latitude by 30 Minutes of Longitude. The heights are shown in feet, so 06 is 600' MSL.
The MEF includes a small safety margin. It is provided so a pilot, who is experiencing instrument, mechanical or other on-board failures, knows that if he maintains the MEF as a minimum, he will have terrain/obstacle clearance, while he attends to his other emergencies.
I commend you for referring to a Sectional chart for your flight planning. I urge you to continue to study Airspace & Regulations, well beyond the anemic minimum the FAA required of you, to pass the Part 107.
Here is a link to the FAA Chart User's Guide to assist you in learning all of the chart symbology that is used.
https://www.faa.gov/air_traffic/fli...aero_guide/media/Chart_Users_Guide_12thEd.pdf