it smells

This one you might already know because of the recent-ish protests in Lebanon in which طلعت ريحتكم became a common slogan. Basically, to ‘smell’ (in the intransitive sense of giving off a smell, rather than detecting one as a smelling person) is expressed with two alternatives which are pretty similar – one with Tile3 and the other Talla3:

بقي اكتر من خمس دقايق يشرح لحبيبتو انو الجسم بطلع ريحة
bi2i 2aktar min kham@s da2aaye2 yishra7 la7abiibto 2inno ijjis@m biTalle3 rii7a
He spent more than five minutes explaining to his girlfriend that bodies give off a smell

ولك يا ابو ريحه بدي اتبرعلك بعلبه شامبو بلكي نضفت اف ريحتك طالعه
wlak yaa abu rii7a biddi itbarra3lak b3elbet shaambo belki naDDaf@t 2uff rii7tak Taal3a
You smelly bastard, I want to make you a donation of a bottle of shampoo, maybe you’ll clean up a bit – eugh, you smell so bad!

Note that unlike the English ‘it smells’ (which is a statement of ongoing activity) the Arabic is resultative – you say, literally, ‘its smell has come out’ unless we’re talking about a habit, similar to the distinction between بيلبس and لابس.

This is the literal meaning. The metaphorical meaning of the expression, though, is that something is dodgy and that people are noticing it:

قيم ايدك من المعاملة ريحتها طالعة
2iim 2iidak mn ilmu3aamale rii7itha Taal3a
Leave the project alone, people are onto it/it stinks

When referring to people metaphorically, it tends to mean that someone has done so many bad things that you’re sick of them or that it’s become clear to everyone that they’re bad. This is what was meant in the Lebanese protests – a sort of combination of ‘we’re onto you’, ‘we’re sick of you’ and ‘you’ve gone rotten’:

شو من صار رح تطلع ريحتو و يبان
shu man Saar ra7 tiTla3 rii7to w ybaan
Whatever happens, the bad things he’s done will become noticeable [= his smell will come out] and he’ll be outed [as bad]