Remember also that you're attempting to communicate, so you should expect (even embrace) errors. So it's okay to play it safe and use "en" for words when you are unsure. You'll figure it out in time and person who speaks or is learning to speak will understand. If you get lucky, they will point out your error in a nice way to help you learn. But the gender of a word has one other implications. En katt (a cat) becomes katten (the cat). Ett träd (a tree) become trädet (the tree). So knowing the gender helps establish the correct way to use both the indefinite and definitive version of any noun.

en/ett is the same as 'a or an' in english. For example En katt-a cat Ett hus-a house En vägg-a wall Ett ansikte-a face So as you can see, it seems fairly unpredictable if the words will be en or if the words will be ett. These are also called common (en) and neuter (ett) genders. Most say it is unpredictable, but there are some patterns. You use en MUCH more than ett. the common gender (en) is about 80% of the nouns in swedish. You use common gender on mostly all living things (with a few exceptions), but sometimes it is unpredictable and you'll have to look up if the word is an en/ett word. Any time you would use 'it' or 'that' in English you would normally use the word 'det'. You would use 'det' much more than 'den'. For example, 'It's raining'-Det regnar. You use 'det' because there is no noun in the sentence, and when there is no noun, you have no indication of whether it should be common or neuter.In Swedish, you always use det in that case. The only exception would be if you are pointing at an object that is a common noun like 'chair' or "stol" in Swedish. Pointing at the chair you would say 'Den är blå' Other than that, living persons or animals always take the common (en) gender. When it comes to adjectives there are a few exceptions when describing living things, like 'Ett barn' (a child), 'ett djur' (an animal), 'ett får' (a sheep), etc. Hope that helped :)