What are "Masos"?
Rashi #2: It means 'Nisyonos' (tests).
Targum Onkelos and Targum Yonasan: "Masos" means 'miracles'.
What is the difference between "Osos and Mofsim"?
Rashi: "Osos" are signs, to prove that Moshe was Hashem's Shali'ach. "Mofsim" are wonders (or miracles), such as the ten Makos.
What are "Yad Chazakah" and "Zero'a Netuyah" referring to?
Rashi: "Yad Chazakah" refers to the Makah of Dever (pestilence), and "Zero'a Netuyah", to the sword of Makas Bechoros. 1
Rashi writes that "Zero'a Netuyah" refers to the sword of Makas Bechoros. What was this?
Bartenura: When Moshe announced Makas Bechoros, the Bechoros demanded that Pharaoh release Yisrael; he refused. They made war with the other Mitzriyim, and killed many. We learn from a Gezeirah Shavah to "v'Charbo Shelufah b'Yado Netuyah Al Yerushalayim" (Divrei ha'Yamim 1, 21:16).