Our Mishnah deals with a husband who instructs that a get be written for his wife and makes it conditional on time - that he not return within twelve months. We will examine two versions of the instruction, the difference between them regarding when the get may be written, and the law of a get given close to the husband's death.
The first version - the condition precedes the instruction:
The husband says: "Im lo basi mikan v'ad shneim asar chodesh - kisvu u'senu get l'ishti" - "If I have not returned within twelve months, write and give a get to my wife." On the strength of this instruction they wrote the get within the twelve months, and even though they gave it only after the twelve months, it is not a valid get. The reason: the sense of his words is that the get should not be written until after twelve months, and here the writing was done too early, contrary to his instruction.
The second version - the instruction precedes the condition:
The husband begins by saying: "Kisvu u'senu get l'ishti" - "Write and give a get to my wife," and only afterward adds: "Im lo basi mikan v'ad shneim asar chodesh" - "if I have not returned within twelve months." Here too they wrote the get within the twelve months and gave it after the twelve months, and seemingly the ruling should be the same as in the first case: it is not a valid get.
Rabbi Yose disagrees and holds that in this case it is a valid get. What is the basis of the distinction?
In the first version: the condition was stated first - "If I have not returned within twelve months, then write the get" - and the sense of his words is that the get is not to be written until after twelve months.
In the second version: the husband put the instruction to write first, and only afterward mentioned the condition. For this reason Rabbi Yose understands that the condition refers only to the giving of the get, while the writing may be done at any time. Therefore, even though the get was written within the twelve months, as long as it was given after the twelve months it is a valid get.
Written and given after twelve months and then the husband died:
If they wrote the get after twelve months and gave it after twelve months, and the husband died, we must determine which came first: if the get preceded the death, it is a valid get; and if the death preceded the get, it is not a get. And when the matter is not known, there remains a doubt whether the husband was still alive at the moment the get was given. This is what the Sages meant when they said "megureshes v'einah megureshes" - she is divorced and she is not divorced. The matter hangs in the balance: she is possibly divorced and possibly not divorced.
In summary: we have learned that the order of the husband's words determines when the get may be written. When he put the condition before the instruction, the get is not to be written until after twelve months, and a get written before then is invalid even if it was given at the proper time. When he put the instruction to write before the condition, Rabbi Yose holds that the condition refers only to the giving, and the get is valid even though it was written within the twelve months. And in the case where it was written and given after twelve months and the husband died, everything depends on whether the get preceded the death, and when this is not known she is a doubtfully divorced woman.