The well is the shelf under the bar where they keep liquor at hand for mixing drinks. So, a well brand or house brand is the brand of liquor served when a customer requests a drink by its generic name (e.g. gin and tonic, scotch and soda). It's usually the least expensive brand served, as opposed to more expensive call brands.
In many towns in Ireland, 'well' is a salutation or greeting. Having used the expression all my life, I've never been able to figure out whether it's a kindly-meant enquiry as to whether or not all is well with the person so addressed, or simply an expectant demand for news updates - in my hometown, it always felt like the beginning of an interrogation!
1. <interjection> An expression of surprise or disbelief
2. <adverb> Skilful/skilfully
3. <adverb> Intimately
4. <adverb> informal; extremely 5. <noun> A bored hole into the ground to tap a supply of water, gas or oil
6. <noun> slang; The toilet
1. Well! I never expected John to be THAT good in bed!
2. Well done, Pete
3. I know your motherVERY well...
4. OMG Dat's well good dat! OMGOMG1
5. James, go and fetch a pail of water from the well, there's a good boy.
6. Hold on a second I've gotta use the well...