In many languages other than English, including Middle Eastern languages such as Arabic, Hebrew, and Persian, gender is a very important part of the grammar. All things (nouns) have gender, even if they are not actually male or female. Often many parts of speech vary depending on the gender of the subject or object of the sentence, whereas in English generally only the personal pronouns (he, she, it) and possessive adjectives (his, her, its) change. This is often confusing for native-English speakers learning other languages – or even trying to memorize a few survival phrases. Old English nouns fell into one of three grammatical genders – masculine, feminine and neuter. Looking at some of the vestiges of grammatical gender in modern English can be useful in understanding grammatical gender in foreign languages.
In general, in all languages, including English, nouns that represent males (such as man) are of the male gender and nouns that represent females (such as woman) are of the female gender. In English, almost all remaining nouns are neuter – neither masculine nor feminine and are referred to as it. However, there are a few exceptions – for instance, ships are always female, an unknown dog is generally assumed to be male and a cat, female. Thus, English really has three grammatical genders, but the vast majority of nouns are either neuter or use their biological gender. Many other languages only have 2 genders (this applies to all common Middle Eastern languages) – usually masculine and feminine. In addition, in gendered languages, the masculine and feminine word for biologically gendered items usually only differ by a gender specific suffix and the masculine term is also used to refer to mixed groups – resulting in fewer words to learn for the same number of concepts. For instance, rather than having to learn horse, stallion, and mare; in Hebrew you only have to learn סוס (stallion and horse) and that ה- is a common feminine suffix (note that Hebrew is written right to left) and you can recognize סוסה (mare). There are usually rules for determining the gender of a given noun, so in most cases, if you learn a few simple rules, you only have to memorize the gender of any exceptions. Altogether, this is probably the same amount of memorization – or less! - as would be necessary without grammatical gender.
In gendered languages, the gender of adjectives has to match the gender of the noun it describes. This is often done by appending a feminine suffix to the masculine form of the adjective. Again, this actually results in less memorization than we have in English, where some adjectives are inappropriate for masculine or feminine beings and you have to keep track. For instance, we usually don't refer to women as handsome or men as pretty.
If you are traveling or doing business in another country and need to learn survival phrases, you'll notice that many phrases are different depending on whether you are addressing a man or a woman. While it isn't strictly grammatically correct, a useful way to think about this is that you want to be very polite because you aren't familiar with the language and culture. In English, if you were being very polite, you would liberally intersperse Sir, Ma'am or Miss in your speech and so your statements would also sound different when you were speaking to men versus women.
Don't forget to check out my other Middle Eastern Language articles. If you are looking for more in depth information on grammatical gender and other noun classes, I was very impressed by the Wikipedia article on Grammatical Gender. And if you get frustrated, remember that you didn't learn your first language overnight either!