Haastaa is an old fashined word meaning “to talk” or “to chat”. It’s rarely used in it’s original meaning, but it’s still included in another verb “haastatella” = “to interview” (lit. ~ “make someone to chat” ).
“Toimittaja haastatteli poliitikkoa. ” “The journalist interviewed the politician.”
In modern Finnish, “haastaa” has a spesific meaning “to challenge”, for example “Haastan sinut kaksintaisteluun!” “I challenge you to a duel!”
“Haastava” is an adjective and it means “challenging”, for example, “Kisa oli hyvin haastava” “The race was very challenging.”. The noun derived from “haastaa” is “haaste“, “a challenge”. “Otan kaikki vaikeudet haasteena” / “I will take all the difficulties as a challenge”.
In Finnish, to “sue somebody” is literarily “to challenge somebody into court” = “haastaa oikeuteen“. (see the an article for “oikeus”)
Many words releted to concepts such as “middle” or “centre” are derived from the root “keski-“. For example keskusta ~ centre and keskellä ~ in the middle. “Kaupungin keskusta on kaupungin keskellä”/ “The city centre is in the middle of the city”
Keskusta means also the political centre, or the Finnish Centre party, Keskusta puolue.
The historical Middle ages are “keskiaika“, but when a person is middle aged, he is “keski-ikäinen“.
Wednesday is “keskiviikko“, because it’s in the middle of the week (as “Mittwoch” in German).
If something is unfinished, you are probably in the middle of the progress, that’s why: unfinished ~ kesken.
Keskellä means also “in between”. For example, “Maija istuu Pekan ja Villen keskellä.” / “Maija is sitting in between of Pekka and Ville”.
Conversation is communication between two or more people. That’s why conversation ~ keskustelu.
Two more verbs derived from this root are keskittää and keskittyä ~ concentrate.
Niin metsä vastaa kuin sinne huudetaan. / The forest answers in the same way one shouts at it.
This proverb means that your deeds have their consequences and the English equivalent would be “What goes around comes around”.
“Sitä niittää, mitä kylvää” comes from Bible: “You reap what you sow.” Other proverbs with the same meaning are “siten makaa miten petaa” / As you make your bed, so you must lie on it and “sitä saa, mitä tilaa”/ “you get what you order”.
Hänellä on ketunhäntä kainalossa. / He has a fox tail under his arm.
The cunning fox is a metaphor for dishonesty, so hiding a fox tail refers to some kind of dodginess. A similar idiom exists in English: “a wolf in sheep’s clothing”, and it’s also a common saying in Finnish: “Hän on susi lammasten vaatteissa.”
Another idiom related to suspicious things is “Juttuun oli koira haudattuna.” / “There’s a dog buried in it.” In English, you’d probably say something like “there’s something fishy about it” or “I smell a rat.”