As indicated in the Gurbani, the hell is not somewhere up there or there yonder. But, it is here and now.
According to the Gurbani, attachment (Moh-ਮੋਹ) and doubt (Bharam-ਭਰਮ, misapprehension, confusion, etc.) constitute the horrible hell. And many (“ਘਣੋ”-numerous, gross, large number) of us in this world who are sunk (drowned, absorbed-”ਬੂਡਤ”) in this horrible hell (“ਮਹਾ ਨਰਕ”) of attachment and doubt (“ਮੋਹ ਭਰਮ”) are its dwellers (ਵਾਸੀ). The Gurbani:
 

• ਮੋਹ ਭਰਮ ਬੂਡਤ ਘਣੋ ਮਹਾ ਨਰਕ ਮਹਿ ਵਾਸ ॥: Moh bharam buudat ghano mahaa narak mahi vaas (sggs 297).

Perversions or faults of the false ego-sense or Haumai are countless (lust, anger, greed, etc., and their countless variations such as slander, selfishness, falsehood, and so on).
Since attachment (Moh-ਮੋਹ) and doubt (Bharam-ਭਰਮ) are the faults of the false ego-sense or Haumai, the hint here is towards the egotism (Haumai) being the horrible hell. The Gurbani:
 

• ਹਉ ਵਿਚਿ ਨਰਕਿ ਸੁਰਗਿ ਅਵਤਾਰੁ ॥: Hau vich narak surag avataar (sggs 466).

Here, as asserted by the Gurbani, one thing seems to be pretty clear: the meaning of hell (or heaven) many of us often hear from our respective priest-class (Bhais, Pundits, Maulvis, Paadrees, Rabbis, and so on) is not the real meaning of these terms! The Gurbani says that the Gurmukhs (Sant, Bhagat, Realized ones…) have rejected them, both hell and heaven (ਰਦ ਕੀਤੇ, ਖੰਡਨ ਕੀਤੇ, annulled, rescinded…). That is, only the Manmukhs believe them (that hell or heaven is up there, or there yonder, etc.).
 

• ਕਵਨੁ ਨਰਕੁ ਕਿਆ ਸੁਰਗੁ ਬਿਚਾਰਾ ਸੰਤਨ ਦੋਊ ਰਾਦੇ ॥: Kavan naraku kiaa suragu bichaaraa santan do-oo raade (sggs 969).

In nutshell – as the Gurbani indicates – the hell is the Manmukh lifestyle, the Saakat lifestyle, the Mayaic lifestyle (ਮਾਇਕੀ ਜੀਵਨ), the life dictated by the unstable or conditioned mind, the life devoid of the Naam (Shabad-Vichaar, Aatam-Giaan…), the life of ignorance (ਅਗਿਆਨਤਾ)…
 

• ਇਕਿ ਖੜੇ ਰਸਾਤਲਿ ਕਰਿ ਮਨਮੁਖ ਗਾਵਾਰਾ ॥: Eki kharre rasaatali kari manmukh gaavaaraa (sggs 1081).
• ਮਹਾ ਮੋਹਨੀ ਮੋਹਿਆ ਨਰਕ ਕੀ ਰੀਤਿ ॥੧॥: Mahaa mohanee mohiaa narak kee reeti (sggs 815).
• ਮਨੂਆ ਡੋਲੈ ਨਰਕੇ ਪਾਈ ॥: Manooaa dolai narake paaee (sggs 906).
• ਹਰਿ ਸਿਮਰਨ ਬਿਨੁ ਨਰਕਿ ਪਾਹਿ ॥: Hari simaran binu naraki paahi (sggs 1192).
• ਨਰਕਿ ਪਚਹਿ ਅਗਿਆਨ ਅੰਧੇਰੇ ॥: Naraki pachahi agiaan andhere (sggs 1029).
• ਨਿੰਦਾ ਕਰਿ ਕਰਿ ਨਰਕ ਨਿਵਾਸੀ ਅੰਤਰਿ ਆਤਮ ਜਾਪੈ ॥: Nindaa kari kari narak nivaasee antari aatam jaapai (sggs 1013).
• ਜਿਸ ਕੈ ਅੰਤਰਿ ਰਾਜ ਅਭਿਮਾਨੁ ॥ ਸੋ ਨਰਕਪਾਤੀ ਹੋਵਤ ਸੁਆਨੁ ॥: Jis kai antari raaj abhimaanu. So narakpaatee hovat suaanu (sggs 278).

So, according to the Gurbani, to avoid the hellish life or existence is staying connected with the Mool (ਮੂਲ, Source, Origin, Joti…) within, Practice Truth (ਸਚ ਦੀ ਕਮਾਈ), live the Gurmat (Aatam-Giaan, Divine Knowledge, the Gurbani’s Teaching)…
 

• ਗੁਰ ਕੈ ਬਚਨਿ ਨਰਕਿ ਨ ਪਵੈ ॥: Gur kai bachani naraki n pavai (sggs 177).
• ਸਾਧ ਕੈ ਸੰਗਿ ਨਰਕ ਪਰਹਰੈ ॥: Saadh kai sangi narak paraharai (sggs 272).
• ਗਲੀ ਭਿਸਤਿ ਨ ਜਾਈਐ ਛੁਟੈ ਸਚੁ ਕਮਾਇ ॥: Gallee bhisti na jaaeeai shutai sach kamaai (sggs 141).

In nutshell, the Gurbani urges us to make the effort (Shabad-Vichaar…), and switch from the Manmukh-lifestyle to the Gurmukh-Lifestyle (Bhagat or Saintly Life, Jeevan Mukta, Divine Life, Awakened Life…).
 

• ਜਿਤਨੇ ਨਰਕ ਸੇ ਮਨਮੁਖਿ ਭੋਗੈ ਗੁਰਮੁਖਿ ਲੇਪੁ ਨ ਮਾਸਾ ਹੇ ॥੧੨॥: Jitane narak se manmukhi bhogai gurmukhi lepu n maasaa he ||12|| (sggs 1073).
• ਉਦਮੁ ਕਰਤ ਹੋਵੈ ਮਨੁ ਨਿਰਮਲੁ ਨਾਚੈ ਆਪੁ ਨਿਵਾਰੇ ॥ … ਐਸੀ ਨਿਰਤਿ ਨਰਕ ਨਿਵਾਰੈ ਨਾਨਕ ਗੁਰਮੁਖਿ ਜਾਗੈ ॥੪॥੪॥੪੩॥: (sggs 381).