This is a breakout board of SI8641, designed to be used as an SPI Digital Isolator. Which can isolate the master and slave circuit.

Here are some brief information from the datasheet of SI8641

• The working voltage for both side are 2.5V - 5.5V
• High-speed operation
• DC to 150 Mbps
• No start-up initialization required
• Wide Operating Supply Voltage
• 2.5–5.5 V
• Up to 5000 VRMS isolation
• Reinforced VDE 0884-10, 10 kV surgecapable (Si864xxT)
• 60-year life at rated working voltage
• High electromagnetic immunity
• Ultra low power (typical) 5V Operation
• 1.6 mA per channel at 1 Mbps
• 5.5 mA per channel at 100 Mbps 2.5V Operation
• 1.5 mA per channel at 1 Mbps
• 3.5 mA per channel at 100 Mbps
• Tri-state outputs with ENABLE
• Schmitt trigger inputs
• Selectable fail-safe mode
• Default high or low output (ordering option)
• Precise timing (typical)
• 10 ns propagation delay
• 1.5 ns pulse width distortion
• 0.5 ns channel-channel skew
• 2 ns propagation delay skew
• 5 ns minimum pulse width
• Transient Immunity 50 kV/µs
• AEC-Q100 qualification
• Wide temperature range
• –40 to 125 °C

And since this is a breakout board, I will suggest reading the datasheet to understand more about this chip before buying. https://www.silabs.com/documents/public/data-sheets/si864x-datasheet.pdf