Hún hringdi grátandi í vinkonu sína, en vinkonan róaði hana strax.

Grátandi is the present participle of að gráta (to cry). Here it works adverbially, describing how she called: crying, while crying, or in tears.

So:

• Hún hringdi grátandi ... = She called, crying ...

It does not carry the tense by itself. The past tense is in hringdi.

Because Icelandic uses the expression að hringja í einhvern, which means to call someone on the phone.

So the pattern is:

• hringja í + accusative

That is why you get:

• í vinkonu sína

Even though English says call someone without a preposition, Icelandic normally uses í here.

Because vinkona is the dictionary form, the nominative singular. After hringja í, the noun goes into the accusative.

So:

• nominative: vinkona = female friend
• accusative: vinkonu

That is why the sentence has:

• í vinkonu sína

Sína is a reflexive possessive. It refers back to the subject of the same clause, which is hún.

So:

• í vinkonu sína = to her own friend

This is the normal Icelandic way to say that the friend belongs to the subject of the clause.

If you used hennar, it would usually mean her friend in a non-reflexive sense, referring to some other female person, not the subject herself.

Also, sína agrees with the noun it belongs to:

• vinkonu is feminine singular accusative
• therefore the possessive is sína

Vinkonan means the friend. Icelandic often adds the definite article to the end of the noun.

So:

• vinkona = a friend
• vinkonan = the friend

In the second clause, it refers back to the friend already mentioned in the first clause, so English naturally says the friend and Icelandic uses the definite form vinkonan.

Because róa einhvern (to calm someone) takes a direct object in the accusative.

So:

• nominative: hún = she
• accusative: hana = her

That is why the sentence says:

• vinkonan róaði hana strax = the friend calmed her immediately

Both are past tense, 3rd person singular verb forms.

• hringdi = called
• róaði = calmed

They match the singular subjects:

• Hún hringdi ...
• vinkonan róaði ...

So this sentence is narrating two past actions.

This is normal Icelandic main-clause word order. Icelandic is a verb-second language, which means the finite verb usually comes early in the clause.

In this clause:

• vinkonan = first element
• róaði = second element

Then come the other parts:

• hana
• strax

So the order is completely natural.

You can sometimes move adverbs around for emphasis, but this version is the straightforward neutral order.

Strax means immediately, right away, or at once.

In this sentence:

• vinkonan róaði hana strax = the friend calmed her immediately

Its placement here is very natural. Icelandic does allow some flexibility with adverb placement, but strax at the end of the clause is a common neutral choice.

No, in this kind of use grátandi stays the same. The -andi participle is commonly used as an indeclinable form.

So even though the subject is feminine singular (hún), you still say:

• hún hringdi grátandi

You do not change grátandi to match hún.

Because the sentence has two coordinated main clauses joined by en (but):

• Hún hringdi grátandi í vinkonu sína
• en vinkonan róaði hana strax

The comma helps separate the two clauses clearly. This is very normal punctuation in Icelandic.

Yes. Vinkona means a female friend.

Compare:

• vinur = male friend
• vinkona = female friend

So this sentence specifically says that she called a female friend, and that female friend calmed her down.