Mishnah 2 in the third chapter of Kiddushin expands on the various conditions a man may stipulate in the process of betrothing a woman.
"Al menas she'etein lach masayim zuz":
If a man says to a woman, "Harei at mekudeshes li al menas she'etein lach masayim zuz" - "You are betrothed to me on condition that I give you two hundred zuz" - then "harei zo mekudeshes v'yitein" - she is betrothed, and he must give. In other words, the betrothal takes effect provided that he gives her the two hundred zuz, since he made the betrothal dependent on this payment.
"Al menas she'etein lach mikan v'ad sheloshim yom":
Here the man set a time limit for fulfilling the condition, and the ruling of the Mishnah divides into two cases:
He gave her the money within thirty days - the condition was fulfilled, and she is betrothed.
He did not give within that period - she is not betrothed.
The Gemara clarifies the novelty of this ruling: we do not say that by specifying thirty days the man did not intend a genuine condition, but only meant to press himself so that he would hurry to make the payment. We establish that his intent was an actual condition, and therefore if he did not give within thirty days, the betrothal does not take effect.
"Al menas sheyeish li masayim zuz":
One who betroths a woman on condition that he has two hundred zuz in hand - "harei zo mekudeshes b'yeish lo" - she is betrothed if he indeed has it. If it was clarified, for example through witnesses, that he really does have two hundred zuz, the betrothal takes effect. But if the matter was not clarified, she is betrothed out of doubt. The reason for this: it is possible that he really does have two hundred zuz, and nevertheless he wishes to entangle her and lead her to believe that she is not married - so that she will go and marry someone else, and then he will produce the two hundred zuz and create severe problems. For this reason, as long as we have not been able to determine whether or not he has two hundred zuz in hand, she is betrothed out of doubt.
"Al menas she'ar'eich masayim zuz":
If he tells her that he will show her two hundred zuz - "harei zo mekudeshes b'her'ah" - she is betrothed once he shows it to her. Here the testimony of witnesses that the money is in his possession is not enough; he must actually show her the money.
The Mishnah adds: "V'im her'ah al hashulchan - einah mekudeshes" - and if he showed her money on the table, she is not betrothed. 'Shulchan' here refers to the shulchani, the money changer, who sits at a table on which money is laid out. If he showed her funds belonging to his money changing business - funds deposited with him that are not his own - that is not enough. Even though he has access to this money, it is not his property, and therefore the betrothal does not take effect: when he said he would show her two hundred zuz, his intent was two hundred zuz that actually belong to him.
In summary: In this Mishnah we learned four forms of condition in betrothal. One who betroths on condition that he will give two hundred zuz - she is betrothed and he must give. On condition that he will give within thirty days - if he gave in time she is betrothed, and if not she is not betrothed, since his words constitute a full condition. On condition that he has two hundred zuz - she is betrothed if the matter was clarified, and betrothed out of doubt if it was not. And on condition that he will show her two hundred zuz - she is betrothed once he actually shows it, provided that the money is his own and not the money changer's funds in his possession.