顾不了 is a resultative verb compound meaning 'cannot take care of' or 'have to disregard'. The 不了 (bùliǎo) complement indicates inability to complete the action of 顾 (to attend to, to look after). You use it when you're forced to ignore something because you don't have the time, energy, or resources to deal with it. It's often followed by the thing being neglected, or used standalone as an apology or excuse.