As a native English speaker this sound is really hard for me. It's like half an "Pu" sound and half an "ool" sound. The last bit is what trips me up, how do you pronounce that "ool/eul" sound?
I recommend referring to Forvo for questions like this. Native speaker examples for 풀: https://forvo.com/word/%ED%92%80/
Based on my experience (intermediate) this word sounds very much like English "pool."
However in certain situations (generally if a vowel follows directly after the ㄹ sound) the "L" becomes like a rolled R in Spanish.
Your ears may be detecting a very salient difference between the phonologies of (many accents of) English and Korean.
From page 54 of The Sounds of Korean, 3.8.2 ㄹ in other positions:
When ㄹ occurs [...] at the end of a word that stands alone, as in 불 'fire', it is pronounced with the tongue touching against the dental ridge just behind the teeth. The end result is a sound very much like the 'clear l' that appears at the beginning of English words such as leg and lip [...]
The statement about English goes on to distinguish between clear and dark L in English. Not all accents of English have this distinction, with Received Pronunciation in British English having a fairly robust distinction between the two, General American having the two somewhat closer and darker, and Australian, NZer and Scottish English have a preference for dark L in all contexts.
In contrast, although Korean speakers do have some individual variation in where exactly it is placed in the mouth (apical vs laminal, alveolar vs postalveolar), it is overwhelmingly clearer than the equivalent English /l/ at the end of a word.
/ㄹ/ — The tip of your tongue touches your alveolar ridge.
Say “buTTer” or “daDaDah” in American English. Yes. You just made the flap T sound at your alveolar ridge, where the tip of your tongue goes when you pronounce the “T” or “D” sound. That’s where the /ㄹ/ sound is made. The tip of your tongue should go there at the end. It should touch the roof of your mouth, unlike the dark L sound.