please explain me the calls in advance part alone :)

Category                             Number of Shares Applied                                   Number of Shares Allotted

I                                                   2,20,000                                                              1,50,000 

II                                                 5,50,000                                                              3,50,000 

Excess application money received with applications was adjusted towards sums due on allotment. Balance, if any was adjusted towards future calls. Govind, a shareholder belonging to category I, to whom 1,500 shares were allotted, paid his entire share money with allotment. Manohar belonging to category II, who had applied for 11,000 shares failed to pay 'Second & Final Call money'. Manohar's shares were forfeited after the final call. The forfeited shares were reissued at Rs. 10 per share as fully paid up.