We are learning Maseches Moed Katan, chapter 2, mishnah 5. The mishnah deals with activities that are permitted on Chol HaMoed: protecting fruit from the rain, and selling and craftwork done discreetly for the needs of the festival.
Covering the drying figs:
"Machpin adam ketzios b'kash" - the ketzios are figs left out in the field to dry, and one may cover them with straw so that they will not be damaged by the rain.
"Rabbi Yehudah omer af me'aben" - according to Rabbi Yehudah one may even thicken. Two explanations are offered as to what this means:
One may pile the figs themselves in a thick heap, so that the upper ones protect the lower ones.
The reference is not to piling up the figs, but to covering them with a large amount of straw - not merely a little straw as the first tanna holds, but even a great deal. Even though this gives the appearance of constructing a storage place, something considered beyond what is permitted on Chol HaMoed, Rabbi Yehudah permits it.
Selling discreetly for the needs of the festival:
"Mochrei feiros kesus v'chelim mochrin b'tzin'ah l'tzorech hamo'ed" - sellers of fruit, clothing and utensils may sell discreetly, not in a public manner, for the needs of the festival. The Gemara explains the parameters of discretion in a store:
A store that opens onto the side or into an alleyway: the owner may open its doors as usual.
A store that opens onto the public domain: he must leave one door closed and one door open.
The craftsmen who work discreetly:
The mishnah continues: "Hatzayadin v'hadashoshos v'hagerusos osin b'tzin'ah l'tzorech hamo'ed", and these are they:
Hatzayadin - those who trap birds and catch fish.
Hadashoshos - those who crush wheat into groats.
Hagerusos - those who grind legumes.
All of these may perform their work in a discreet manner for the needs of the festival.
"Rabbi Yosei omer: hem hechmiru al atzman" - the members of these trades took a stringency upon themselves, and did not perform their work on Chol HaMoed at all, even for the needs of the festival and even discreetly.
In summary: in this mishnah we learned the permission to cover drying figs with straw to protect them from the rain, and Rabbi Yehudah's opinion permitting even thickening; the permission for sellers of fruit, clothing and utensils to sell discreetly for the needs of the festival, and the parameters of discretion in opening the store; and the permission for the trappers, the wheat crushers and the legume grinders to work discreetly, regarding whom Rabbi Yosei testified that they took a stringency upon themselves and refrained from their work entirely.