This schematic is the internal schematic of a module:
If you are using the module you need only connect it to GND/Vcc and two pins of the Arduino (one digital, one analog). The 4 pins shown on the header (at the 'top' of the PCB) provide those connections. You'll need to find an appropriate library to communicate with the DHT11 if you don't feel like finding the detailed datasheet information and writing it.
Inside the module, there are two separate circuits, independent save for the power and ground. If you are attempting to copy the internal circuit of their module, you can make one or the other, or both.
It is connected to two individual inputs on the Arduino, plus power and ground.
The SS9013 is used as a crude moisture measurement circuit. A resistance between the two probe points of around 20kΩ will give you about 2V out (very roughly).
And the schematic has nothing, nada, to do with a "reed switch module", very sloppy editing on the part of the seller.
By the way, it passes DC current through the probe so the probe will likely corrode away relatively quickly from electrolytic action. And the circuit is beta-dependent on the individual SS9013 and temperature, so it's very much crude.
The DHT11 is a (possibly legacy) low-cost temperature and humidity sensor module made by Chinese manufacturer Guangzhou Aosong Electronics with a single wire digital interface. All the smarts in this 'product' are inside that module.
All the points marked Vcc are connected together.
All the points marked with the ground symbol are connected together.
You can assemble this on a breadboard, a PCB, perf board, or whatever you like. The wires between the module and the Arduino should not be too long.