The short answer is, all of them that pertain to the New Covenant. What it does not mean is that we observe everything in the Old Covenant.
As we read the New Testament, we observe several important things:
1. The Messiah (Christ) brought the Torah (Law) to completion;
2. The Messiah (Christ) modified or reformed some of the Torah (Law);
3. The death of the Messiah (Christ) on the cross forever abolished the ceremonial Torah (Law).
These are all undisputable facts. We saw in Matt.5:17-18 how He fulfilled or "filled up"/completed Torah where it was deficient. He added new commandments to the old and changed some of the statutes. Gone is the notion "an eye for an eye, and a tooth for a tooth", and in has come a revolutionary new one: "love your enemies, and bless those who despitefully use you". He tightened up the divorce laws. And as the Epistle to the Hebrews teaches, the whole Levitical Priesthood together with the animals sacrifices and ceremonial law has been forever done away with because these things were but shadows of what was accomplished by the Messiah (Christ). And that is quite a big chunk of the Old Testament Torah.
It is beyond the scope of this short essay to go into detail about all of these, but you will find links to the various issues involved on the main page. What the Messiah (Christ) has not abolished is the moral or ethical Torah. All of these statutes remain in perpetuity. The Ten Commandments have not been changed (and especially not the Sabbath), neither the other Mitzvot which the Messiah (Christ) did not abolish. But what has changed is the approach to Torah.