Deforestation means cutting of forests. effects of it are very dangerous like  pollution, less rainfall, soil erosion, damage of ozone layer etc
thanks but it would be better if you elaborate because I wanted an answer in 80-90 words
1.cutting of the tree 2.its effect on ecoiogical balance
cutting opf trees .itis the easy defination
but i wanted an ans. that is easy because in my school notebook it is given in a very lenthy way

1.Cutting down of the trees indiscriminately in the areas of forest or where there a presence of sizable number of trees like plantations is called deforestation.

2.It results in the lowering of the green cover.

3.It affects the ecological balance.

4.It reduces the probability of raining.

5.It affects the soil erosion,it increases the soil erosion.

6.It also affects the sustainability of green cover.