请教各位福友啊，客户说的是什么付款方式？？如何操作啊？？

客户这样说：1. if you speak about order, frankly, ann,i??do not know...this business is not interesting for magin plus even if i buy, i do it with 80-90 days credit ( all big russian importers do this way) because nobody want to invest money for 3 monthes with $1 margin per this product. 2. all biggest factories like （行业公司名, 行业公司名, 行业公司名) give there big russian customers 80-90 days payment terms, otherwise no possible to survive. 3.客户所说的 i do it with 80-90 days credit ，80-90 days payment terms 是什么付款方式啊？ 要如何操作啊？本人从没操作过信用证，请教各位福友啊，我将感激不尽，谢谢你们！