Calculate the area covered by a pixel in Google Earth Engine?

I am doing a project on calculating the growth of urban areas in different cities located in different parts of India.

I have been able to classify the area into urban, vegetation and water.

I cannot calculate the area covered by each pixel. I searched on Google and the available methods use band values, what I need is to find the area covered by urban/water/vegetation based on spectral end-member values that are been defined.

If anyone has the idea on how to perform it please share and if possible suggest an idea to export it into a graph.

Here is a link to the script:

https://code.earthengine.google.com/d5e7c1435a160524404878c6e2110bda

EDIT: my aim to find the growth of an urban area or loss of vegetation in a region over the years. The urban area is indicated in red colour when you run the script.

I am finding how much area is covered by urban area so that I could measure the growth of the region.

I'm fairly new to Earth Engine.