The following article explains two options by which you can extend wifi to another building.
Wireless Point-to-Point Bridge
The first option is to use a wireless point to point bridge. A wireless point-to-point bridge is a device that connects two separate networks wirelessly by building a point to point wireless link.
To set this up, you need to have a clear line of sight between the buildings. A wireless point to point bridge comes in pairs of two wireless access points.
The UeeVii 5.8G Outdoor CPE Point to Point Long Range Access is a good choice for a wireless point to point bridge.
It is a pair of two access points which is then configured to setup a point to point wireless link. The first access point is setup on the first building and the second access point on the other building to which the wifi signal has to be extended.
More details of the device can be checked on Amazon here – UeeVii 5.8G Outdoor CPE Point to Point Long Range Access
Outdoor Wi-Fi Access Point
The second option is to use a outdoor wifi access point. The outdoor access point is typically connected to the main network in the building 1 , which is then used to transmit the wifi signal to the second building.
The WAVLINK AC1200 Outdoor Wireless High Power Weatherproof WiFi Long Range Extender/Access Point/Mesh is a good choice for outdoor access point.
Wireless point to point bridge vs outdoor access point
A wireless point-to-point bridge is ideal when you want to connect two networks which are in two different buildings. This acts like a leased line for connecting two offices.
In this case, a wireless link between two access points are established for establishing the leased line.
For this setup, a clear line of sight is required, without which it would be not possible to setup a point to point bridge.
An outdoor access point is ideal when you want to just extend your wifi coverage to another building in the vicinity. For example, this could be a nearby barn or a building with an open space where wifi from the main building has to be relayed.
An outdoor access point is not recommended when you need to connect two buildings.
Conclusion
A wireless point-to-point bridge is a recommended choice if you need to connect two separate buildings wirelessly while an outdoor access point is recommended if wifi coverage has to be provided to a large area like a barn or parking space.
The type of product need to be selected based on the deployment environment.
Recommended products
Wireless Bridge Gigabit High Speed, ５𝐊𝐌 UeeVii CPE850 5.8G Point to Point WiFi Outdoor CPE
TP-Link EAP610-Outdoor | Omada True WiFi6 AX1800 Gigabit Outdoor Access Point