It interprets where it needs to jump and then jumps to the precompiled binary machine code locations that are executed natively on the CPU, no interpretation going on (I guess it's conceptually something like instruction traces inside the CPU trace cache, but done at higher level). These precompiled building blocks are shipped in separate libraries, one library for each CPU architecture on a platform (SSE4.2, AVX, AVX2, AVX-521 on AMD64 and other SIMD architectures on other platforms that Oracle supports). Oracle dynamically loads the correct library matching the CPUs capability during the startup and starts jumping there as needed.
So this is not bytecode interpretation, it's native machine code executed directly on CPU whenever the SQL exec engine decides to jump there. This is different from, say Apache Impala that compiles new LLVM machine code for each query execution for the query's scanning tight loops.
Edit: I guess why I see this as not just not regular bytecode interpretation (I don't actually know that much about it in general), is that these building blocks can include various loops (and can do their thing on entire vectors of data), so looks like they can push quite a bit of complexity into the machine code sections, before returning back to the normal interpreted AST/opcode land.