What exactly is Wire.Write() function?

What exactly is Wire.Write() function? I read from the site: "It Writes data from a slave device in response to a request from a master". What does this mean?
Does it mean we are writing data to the slave or reading data from slave? I dont understand what this function do. Can you guys please explain me with an example ?

Have you looked at WireWrite()

As explained on that page the function

Writes data from a slave device in response to a request from a master, or queues bytes for transmission from a master to slave device (in-between calls to beginTransmission() and endTransmission()).

The page has an example of the latter usage

What exactly is Wire.Write() function?

It is a function that writes data over the I2C bus. This is a protocol for connecting many devices ( up to 127 devices ) over the same two wires.

Wire.write(0x25); instruction stores/queues the data byte (0x25) in a buffer. At the Master side, the Wire.endTransmission(); tells the MCU to get the data byte from the buffer and send it to Slave using I2C bus/protocol and then brings STOP condition on the bus.

Prior to sending 0x25 over the bus, the MCU brings START condition on the bus, checks the presence of the slave on the bus by sending its 7-bit address through the execution of this code: Wire.beginTransmission(slaveAddress);.

Finally, the sequence of codes are:

Wire.beginTransmission(slaveAddress);
Wire.write(0x25);
Wire.endTransmission();