Let’s talk about one of the first things that comes up in almost any discussion of Finnish among people who find the language scary: noun cases. Usually discussions like this lead to people enthusiastically explaining how many of these there are, and how they would never be able to remember all of them. This, of course, is the root of problem, so let’s try and dispel that myth.
Now, first, I want you to forget everything you know about Finnish grammar. Imagine you’re encountering the language for the first time, and perhaps you don’t even know how it’s normally written. With that in mind, imagine someone showed you the following sentence:
It’s probably going to be pretty obvious what it means: each element corresponds pretty closely to an English word in the translation “S/he lives in Oulu”, with only two elements — those corresponding to “Oulu” and “in” — being “out of order” in comparison to the English. If I gave you a few more sentences like this (I’m going to pass for now, to keep this post to a manageable length), you’d quickly realize that this is the norm in Finnish: the elements with meanings that in English are expressed by prepositions generally go after the noun.
So how hard is this exactly? In my opinion, not very. Yes, you have to get used to something new, but you also have to get used to a bunch of new words anyway, so there isn’t much additional complexity there.
Now, to get from the sentences above to normal Finnish, all you have to do is remove the space between the noun and the element corresponding to a preposition in English. In speech, this means that they are pronounced together as one word, without any secondary stress on the second element. This, and the fact that vowel harmony and consonant gradation are also sometimes present (we’ll talk more about those later on), are the only reasons why linguists treat -ssa, -lla, and other elements as endings rather than just postpositions.
As an exercise, try talking and writing about who lives in the cities and towns Oulu, Inari, Vantaa, Espoo, and Pori, as well as in a house (talo). You can play around with other words as well, but recognize that there are other processes affecting them as well, and you might get slightly odd forms if you start from those words without reading the next couple of sections.