the world we see today is a result of both evolution and succession? explain in easy words

Dear student,

To put in simple words, 

Evolution - This term stems from 'evolve' or to develop over a period of time.

Succession- Means to succeed over an old organism /to establish dominance by a new species over an existing species.

The above written statement in your question thus means that, whatever diversity in organisms we are currently witnessing in our environment....it has come about over millions of years of constant development in the habit ,nature, morphology, anatomy of these organisms as it was required by nature (natural selection and adaptations). 

     It was'nt the same always. It has developed from simple forms to more sophisticated ones, and is still developing.

      Also , among species of similar kind, whenever there was successful adaptation in some of them , they automatically flourished more in nature as compared to other species(natural selection) and hence were able to succeed over its contemporaries, increase their population and hence dominate .