Learn Hardcore Finnish: Herätyskello soi aikaisin tänä aamuna.

Herätyskello is a compound noun (written as one word in Finnish). It’s formed from herätys – awakening or alarm, and kello – clock, so it literally means alarm clock.

What part of speech is soi, and which tense does it represent?

Soi is the third-person singular form of the verb soida (to ring). In Finnish the 3rd-person present and imperfect (simple past) can look identical, so context decides. Here, with tänä aamuna, it’s understood as “rang.”

Why are there no articles like a or the in the sentence?

Finnish has no definite or indefinite articles. A noun by itself can mean “a clock,” “the clock” or simply “alarm clock” – context tells you which.

What does aikaisin mean and what role does it play here?

Aikaisin is an adverb meaning early. It modifies the verb soi, indicating that the alarm rang at an early time.

Why is tänä aamuna in this particular form, and what case is aamuna?

Tänä aamuna comes from tämä aamu (this morning) in the essive case, which Finnish often uses for specifying “when” something happens.

tämä → tänä
aamu → aamuna

What’s the difference between tänä aamuna and tänään aamulla?

Both can translate as “this morning,” but

tänä aamuna (essive) treats “this morning” as a time period
tänään aamulla (adessive) emphasizes “during this morning.”
In everyday use they’re largely interchangeable with only a slight nuance.

How flexible is the word order in this sentence? Could we say Tänä aamuna herätyskello soi aikaisin?

Finnish has relatively free word order. You can front tänä aamuna or move aikaisin elsewhere for emphasis. The neutral order is Subject–Verb–Adverb–Time, but swapping elements is perfectly acceptable.