Final answer:
The phrase refers to guidance received from family members who have experience in what the speaker is undergoing, implying they are sharing wisdom from their own journey.
Step-by-step explanation:
The phrase "my cousins who have made the journey send this advice" is a metaphorical expression which signifies that the speaker is receiving guidance from family members who have experienced a similar situation or embarked on a similar venture. These cousins, having undergone the same journey (either physically or metaphorically), have wisdom that they are imparting to the speaker. This could allude to any form of life's journey, be it migration, personal growth, or a career path, where the insights of those who have already traversed that path can be invaluable.