מעשר שני והקדש שנפדו:
If the owner redeems his item he must pay an additional Chomesh (20%)
לא קבע:
He is not set because he is coming and going
Shelo Shimesh:
This refers to Gemara which is based on logic. It is the reasoning behind the Gemara. It is compiled of all the statements, and questions, and answers.
Shelo Nitla Terumato
You might have thought that it is talking about Terumat Ma’aser but it’s not, it’s talking about Teruma Gedola.
Peshita
What is bothering Rashi?
What is simple about this case?
The fact that you don’t make Zimun on Tebel is obvious.
Why does Rashi telling us this?
That is obvious?
Rashi is telling us that now we’re switching to the ones in which you can’t make Zimun.
Neil Shweky 