Well, today in Greek we have to discuss gender. Just can't put it off any longer. Thankfully, it's only grammatical gender we'll be discussing. Now in English, this isn't too big of a deal. Male beings are masculine. Female beings are feminine. And if something is nether masculine nor feminine, it's called "neither" (neuter). Greek is not so accommodating. Neither is Spanish for that matter. (I tend to use Spanish in my illustrations because if a student has studied a language before taking Greek, it's likely to have been Spanish.) In Spanish, a table (mesa) is feminine, while a ship (buque) is masculine. And, as far as nouns is concerned, there is no neuter gender at all. So you see, it's not so much a matter of sexual gender as of the termination or derivation of the word.
As if that isn't bad enough, languages with grammatical gender have some really crazy exceptions. For example, in Spanish you use agua for "water." The word is feminine, as are most words that end in -a. You might therefore expect "the water" to be la agua, since "la" is the feminine article in Spanish. However, in Spanish you would actually say el agua, using the masculine form of the word for "the" -- probably for ease of pronunciation (you avoid the combination of two "a" sounds). Now, here's a picture from my textbook.
Here you can see how some Greek nouns are masculine, some neuter, and still others feminine. It will be worth your while to study this lesson carefully, because you will see there are a number of clear patterns in Greek. Of course, there also have to be exceptions, right? At all events, don't despair when it comes to this thing called gender. I had never heard of the concept until I took Greek, but you get adjusted to it rather quickly!
Have a wonderful day!