Here are the main grammatical elements in Spanish and some useful information about them:
A noun is a word which is mostly used to refer to a person or thing. All nouns in Spanish have a gender, meaning that they are either masculine or feminine. For example, "niño" (boy) is masculine and "niña" (girl) is feminine. The best way to identify gender is undoubtedly experience, although here are some general guidelines which may be useful at the beginning: usually nouns ending in –o are masculine and nouns ending in –a are feminine. Of course there are always exceptions.
For example, "mano" (hand) and "radio" (radio) are feminine. On the other hand, words of Greek origin ending in –ma, such as "dilema" (dilemma) or "problema" (problem) are masculine. When you are learning new vocabulary, it is recommendable that you learn a noun together with its corresponding article. That will help you to remember their gender. For example "la niña", "la mano" or "el problema" and "el niño".
Adjectives are used to qualify a particular noun, to say something about it. It is important to remember that in Spanish they are usually placed after the noun. Since adjectives are always related to a noun, they have to agree with them in gender and number.
This means that if you want to say something about the noun "niño", which is masculine and singular, the adjective that you use will also have to be masculine and singular. Thus, you can say "niño alto" (tall boy), "niño pequeño" (small boy), etc. If, on the other hand, if you were talking about a girl, you would have to say "niña alta" and "niña pequeña".