While the answer of Michael Stachowsky and the comments under that provide the answer to what you're seeing, I think some more context can be helpful.
The plots shows are a product from the NOAA Space Weather Prediction Center, which, as the name implies, is a weather center for space weather. This is a conceptual term to describe the time-varying conditions in the solar system, in particular around the Earth. Two important components of space weather are the particles emitted by the Sun (solar wind) and the interaction of the Earth's magnetic field with the interplanetary magnetic field.
The reason people are interested in space weather is because of the impact space weather has on us: small weather events upset satellite communications, larger events can cause serious damage on Earth (see solar storm of 1859).
The Advanced Composition Explorer (ACE) satellite has been monitoring space weather since 1998. Since 2016 the Deep Space Climate Observatory (DISCOVR) is the primary provider for space weather data, although ACE is still operational and used as back-up. The DISCOVR real-time solar wind parameters can be found here.
Both are at the L1 Lagrange point and can provide us with an early warning of space weather upsets about an hour in advance.
Now to explain wat we're seeing:
- $B_t$ is the total field strength of the interplanetary magnetic field (IMF). $B_z$ is the component perpendicular to the ecliptic plane (i.e. the component that more-or-less aligns with the Earth's north-south axis and thus its magnetic field. The Earth magnetic field has its north pole in positive $B_z$ direction, so if the IMF points in negative $B_z$ direction, the field lines will connect and allow charged solar particles to flow into the Earths magnetosphere.
Earth's magnetic field in the XZ-plane with the Sun on the left. The Earth's magnetic field protects us from the solar wind (source).
When the IMF points south, the field can connect with Earth's magnetic field (source).
- $\phi$ is the angle that the IMF makes in the XY plane. This is due to the rotation of the Sun which tangles up its magnetic field like a spiral (Parker spiral). In addition, every now and then (11 years or so), the Sun's magnetic north and south poles flip.
(source: nasa.gov)
Impression of the IMF (Parker spiral) (source).
- The last three graphs indicate the "intensity" of the solar wind: density is the number of particles (originating from the Sun, e.g. during a coronal mass ejection (CME)) per unit volume, cubic centimeter in this case. Speed, in kilometers second, is the speed of these particles and Temp is the temperature in Kelvin.
The whole interaction between IMF and the Earth's magnetosphere is pretty complicated and probably Astronomy.SE can give much better explanations than what I can give here.
(source)
Popular websites like Spaceweather.com and Spaceweatherlive.com focus on the possibility of seeing aurora's ("Northern lights"), which can occur if the IMF is strong ($B_t > 30$ nT), pointing southwards to allow the connection of the field lines ($B_z < -10$ nT) and a lot of hot, fast, charged particles (high density, speed and temperature), which are conditions that were showing in the graphs on the 27th ("aurora's not guaranteed"). Often, you'll see these numbers aggregated in a single number called the $K_p$ index, which is a measure for the intensity of space weather and its impact on Earth. Often, $K_p > 5$ is a sign to watch out for aurora's.
However, as you can see on this page of NOAA SWPC, there is a lot more to worry about than pretty lights.
