1. prepare or provide the basic idea(s) or structure(s) for something
lay the foundation/groundwork for success/a deal/career
When you 'lay the foundations' for something it means to create a base upon which other structures or larger ideas are built. You lay foundations before building a house for example or you could say that Darwin's theory of evolution laid the foundations for modern evolutionary theory. To 'lay the groundwork' has a similar meaning of creating a foundation for something or to put in the necessary work for something to begin.