That is saying 'There is no power and no strength except through God.' For one who says it often in a dream, it signifies a warning of something that calls for saying it. Likewise saying 'To God we belong and to Him we return' signifies a warning of something that calls for saying it, and it may signify a calamity.
Dream meaning · al-Nabulsi
Saying la hawla wa la quwwata illa billah حوقلة
Source: al-Nabulsi, Ta'tir al-Anam fi Ta'bir al-Manam, p. 95. English translation by iDreamBot. Quran verses: Quran.com, Saheeh International.