What is meaning of an act being makrooh/ unrecommended to perform? Does it mean performing that act makes you one step close to a haram act or does it mean it reduces the sawaab of that act a little

We have two types of Makrouh acts. The first type is acts of worship. For example, praying a Mustahab prayer at certain times (like later afternoon) is Makrouh. Or reading Qur’an while in the state of Janaba or Haydh us Makrouh. In these instances, Makrouh simply means less reward, since the act itself is a good act. Then we have non-worship acts, such as sleeping between dawn and sunrise. With most Makrouh acts, they either decrease the blessings in one’s life, or as you stated, then might make sins more accessible and bring you closer to committing them.