section 78

"Where a change has occurred in the constitution of a firm, nothing in this Chapter shall entitle the firm to have carried forward and set off so much of the loss proportionate to the share of a retired or deceased partner as exceeds his share of profits, if any, in the firm in respect of the previous year."

What does the line 'as exceeds his share of profits, if any, in the firm in respect of the previous year' means? please explain,thanks in advance