C'est or Il est

Rahul,

 have a look at section 2b of the linked lesson which discusses this and gives examples. 

“ Mon stylo est sur la table. ________ est sur la table “ 

This is a specific statement about ‘ Mon stylo …’, as described in the section mentioned.  It is not a general statement about pens, or anything else, and ‘ il est sur la table ‘ is correct in this case. 

"C'est" vs "Il/Elle est" to say it is/she is/he is in French

    In those cases, the opinions expressed relate to specific items, we know precisely what we're talking about, whether it be my jumper (not jumpers in general), your plate or that specific bed.
Therefore, here we use il est or elle est, depending on the gender of the thing it refers to (remember that things have genders too in French!).