Israel does not have a language (שפה) requirement, however it is a good idea to know Hebrew (עברית) before coming on Aliyah(עליה). Some countries have a language requirement for new immigrants. If you want to become a citizen of Great Britain, you have to pass an English language test.
Dealing with the government (ממשלה)
If you are making Aliyah from another country (ארץ) and have started the process there, then the Jewish Agency personnel will speak your language. But from the moment (הרגע) that you land in Israel, the government officials most likely will only speak Hebrew. You need to be able to communicate (לתקשר) and get your needs met by speaking Hebrew.
Getting into an Ulpan
Even getting enrolled into an Ulpan, (אולפן) the Hebrew language school that the Jewish Agency (סוכנות) offers, you need to speak a bit of Hebrew to complete the paperwork (ניירת). Then once you are in class (בשיעור), you will learn more Hebrew. You will be able to be in a higher level class if you have learned Hebrew beforehand (לפני). For example(לדוגמה), I was able to at least read Hebrew before I enrolled into the Ulpan. So instead of being in a lower level class, I was in the highest level class and when I graduated, I was able to go and get a job right away. My mother, on the other hand, didn’t know any Hebrew, so she was in a lower level class and didn’t have the skills to get a job when she graduated.
Getting an apartment (דירה)
If you are not offered a Absorption Center (מרכז קליטה) apartment, you will need to find housing for yourself and your family. Even though English (אנגלית) is a required subject in the Israeli school דsystem, not many Israelis really remember their high school English. The rental contracts are all in Hebrew, and it is best to be able to read the contract (חוזה) yourself and not have to rely upon (לסמוך על ) a friend to translate (לתרגם) for you.
Getting a Job
Even if you are in Ulpan, and the classes are provided to you by the Sochnut, you still might need to work (לעבוד), at least part time (משרה חלקית) You will be better able to work, if you have learned Hebrew.
In conclusion, because of all these factors, it is a very good idea to learn Hebrew before you come on Aliyah.
Vocabulary: know Hebrew before you make aliya