In general, "tof" is used to express a positive opinion on a subject. It is often used informally, and the "level of positivity" depends on context, see the examples.

1. great, smashing, cool [adjective; ‘tof‘]

Examples:
– "Toffe actie!"
("Well done!" Lit.: "Great/cool action!")

– "Nicole is een toffe meid, vind je niet?"
("Nicole is a great girl, don’t you think?")

– "Dat was een tof verjaardagsfeest gisteren!"
("That was a smashing birthday party yesterday!")

– "Sander en Marc zijn toffe peren 🙂 ."
("Sander and Marc are great guys 🙂 ." Lit.: "…are great pears…" An expression which can only be used for men…)

– "Vind jij ‘Kiss’ van Prince ook zo’n tof nummer?"
("Do you also think that ‘Kiss’ by Prince is such a cool song?" "Nummer" literally translates to "number", but – depending on context – can also translate to "song".)

2. decent, OK, okay [adjective; ‘tof‘]

Examples:
– "Frank vindt de meeste van zijn collega’s wel tof."
("Frank thinks most of his colleagues are pretty okay.")

– "Ik ken die jongens niet erg goed, maar volgens mij zijn ze wel tof."
("I don’t know those chaps very well, but I think they are pretty decent." Lit.: "…according to me, they are pretty decent.")

Related words:
– "Gaaf": cool, smooth.
– "Keitof": very cool, only used in province of Noord-Brabant where they put "kei" in front of everything to emphasize 🙂 A "kei" is a cobble stone or boulder.
– "Aardig": nice, friendly.
– "Sympathiek": sympathetic, friendly.
– "Cool": cool.
– "Vriendelijk": friendly.