This refers quite clearly to advanced semiconductors. Axios has an article explaining how the US could make it more difficult for Russia to get semiconductors. The approach is quite simple, as Axios describes it:
As part of Biden's strategy to inflict economic pain on Russia, the administration is threatening to use government regulations to restrict not only chips made by U.S. companies, but chips made by foreign companies that rely on U.S. equipment, tools, software or designs.
Because of the ubiquitous presence of U.S. technology in the chip-making supply chain, the blow to Russia could be staggering.
A spokesperson for the Whitehouse described the technology sanction option in a press call (without mentioning semiconductors explicitly):
In the case of export controls, what we’re talking about are sophisticated technologies that we design and produce that are essential inputs to Russia’s strategic ambitions.
So, you can think of these export controls as trade restrictions in the service of broader U.S. national security interests. We use them to prohibit the export of products from the U.S. to Russia and, potentially, certain foreign-made products that fall under U.S. export regulations.
And given — the reason they work is: If you step back and look at the global dominance of U.S.-origin software, technology, and tooling, the export control options we’re considering alongside our allies and partners would hit Putin’s strategic ambitions to industrialize his economy quite hard. And it would impair areas that are of importance to him, whether it’s in artificial intelligence or quantum computing, or defense, or aerospace, or other key sectors.
In 2021, the Brookings Institute actually wrote an interesting article on Chinese semiconductors entitled Lagging but motivated: The state of China's semiconductor industry. On the US-China relation the article says:
Every year, China imports more than $300 billion of semiconductors, and most, though not all, major American semiconductor companies pull in at least 25% of their sales from the Chinese market.
This mutual dependence has benefitted the technology sectors in both countries. Every major Chinese technology company relies on U.S. chips: Tencent or Alibaba would not be the powerhouses they are today if they had relied on Chinese microprocessors during their formative years or had developed and manufactured their own. Many U.S. companies, meanwhile, have benefited from Chinese customers, markets, and innovations.
I don't know which products would be unavailable to Russia in case of such sanctions. Of course semiconductors are used in a lot of appliances, but which ones rely in some way on US technology and which can be made without, that I don't know. The way I see it though, having to use less advanced technology can set you back quite easily because advances are so rapid. Imagine only having access to technology that has been available for 10 years or more, that's quite restrictive.