What does idle talk mean as I’ve seen it referenced to singing and dancing sometimes but then I heard that it is when you talk about useless things (can’t remember where I heard this from). If it is about talking about “useless” things can we only talk about things related to Islam with friends and colleagues because it’s haram to do otherwise?
Your question is unclear as "idle talk" is not an a standard term. My guess is that you are referring to لهو الحديث which has been mentioned in the Quran and is translated as 'idle talk' by some such as Muhsin Khan.
ومن الناس من يشتري لهو الحديث ليضل عن سبيل الله بغير علم ويتخذها هزوا أولئك لهم عذاب مهين
And of mankind is he who purchases idle talks to mislead (men) from the Path of Allâh without knowledge, and takes it by way of mockery. For such there will be a humiliating torment.
The most prevalent exegesis of the verse is that لهو الحديث means الغناء (singing); this is the tafseer reported from Abdullah ibn Masud, Ibn Abbas, Ayesha, Jabir ibn Abdullah, Abu Umamah, Hasan al-Basri, Mujahid ibn Jabr, Sa'id ibn Jubayr, Ibrahim al-Nakhai and others. While another tradition is that it means the fables of Rostam and Esfandiyār, and there are also other sayings.
As far as singing is concerned, if it distracts from religious obligations or makes one negligent, or involves obscenity, or arouses desires to do something haram - then it is haram.
If it is free from that but used moderately for mundane pleasure then there is difference among the madhabs: some have considered it haram based on the verse and its interpretation, some have considered it makruh, and some have considered it permissible.
And there are some circumstances in which it is permissible, such as during celebrations (e.g. weddings and eid).
There's a difference between a short small talk as an opening for conversation (which is expected in some cultures and fully acceptable) and long talk about nothing.
The transition between acceptable, undesirable and idle talking as well as between important, less important and idle conversation is of course also gradual.
I found a fatwa that unfortunately is not clear about this and it's sources: https://islamqa.org/hanafi/shariahboard/176198/engaging-in-useless-conversation/
What I know is that the Prophet disapproved long idle conversations in the mosque.
gives examples where talking may be bad. It doesn't mention talking about useless topics as a sin, rather as a danger to come into conversation which is haram.
I didn't find any serious quote that talking about unimportant things without talking about something explicitly forbidden is haram. It's only discouraged/disliked if it is excessive.
Our toungues are the biggest source of sins: lying, backbiting, tale telling, etc. The more you talk the more likely you are to commit these major sins, knowingly or unknowingly. Idle talk is useless talk that has no real value, its a waste of time, distracts you from the rememberence of Allah, and hardens one's heart making you less likely to feel the sweetness / enjoyment / peacefulness of worship. It makes worship feel a burden. One can't classify it as haraam, except that it often leads to sinful conversation.
Some talk is necessary: coordination, asking for help, and much is even worship : seeking Islamic knowledge, etc.
This article covers useless talk in more detail: https://www.dawahskills.com/featured-posts/how-to-avoid-useless-conversations-and-idle-talks/
I also recommend reading https://www.dawateislami.net/bookslibrary/en/silent-prince
May Allah save you from idle talk and give you full understanding of this matter.